______________________________________________________________________

  21   Strings library                           [lib.strings]

  ______________________________________________________________________

1 This clause describes components for manipulating sequences of ``char­
  acters,''  where characters may be of type char, wchar_t, or of a type
  defined in a C++ program.

2 The following subclauses describe string classes, and  null-terminated
  sequence utilities, as summarized in Table 1:

                     Table 1--Strings library summary

     +---------------------------------------------------------------+
     |                    Subclause                        Header(s) |
     +---------------------------------------------------------------+
     |_lib.string.classes_ String classes                  <string>  |
     +---------------------------------------------------------------+
     |                                                     <cctype>  |
     |                                                     <cwctype> |
     |_lib.c.strings_ Null-terminated sequence utilities   <cstring> |
     |                                                     <cwchar>  |
     |                                                     <cstdlib> |
     +---------------------------------------------------------------+

  21.1  String classes                              [lib.string.classes]

  Header <string> synopsis

  #include <memory>       // for allocator
  namespace std {
  // subclause _lib.template.string_, basic_string:
    template<class charT> struct string_char_traits;
    template<class charT, class Allocator = allocator,
             class traits = string_char_traits<charT> >
      class basic_string;

    template<class charT, class Allocator, class traits>
      basic_string<charT,Allocator,traits>
        operator+(const basic_string<charT,Allocator,traits>& lhs,
                  const basic_string<charT,Allocator,traits>& rhs);
    template<class charT, class Allocator, class traits>
      basic_string<charT,Allocator,traits>
        operator+(const_pointer lhs,
                  const basic_string<charT,Allocator,traits>& rhs);
    template<class charT, class Allocator, class traits>
      basic_string<charT,Allocator,traits>
        operator+(charT lhs, const basic_string<charT,Allocator,traits>& rhs);
    template<class charT, class Allocator, class traits>
      basic_string<charT,Allocator,traits>
        operator+(const basic_string<charT,Allocator,traits>& lhs,
                  const_pointer rhs);
    template<class charT, class Allocator, class traits>
      basic_string<charT,Allocator,traits>
        operator+(const basic_string<charT,Allocator,traits>& lhs, charT rhs);
    template<class charT, class Allocator, class traits>
      bool operator==(const basic_string<charT,Allocator,traits>& lhs,
                      const basic_string<charT,Allocator,traits>& rhs);
    template<class charT, class Allocator, class traits>
      bool operator==(const charT* lhs,
                      const basic_string<charT,Allocator,traits>& rhs);
    template<class charT, class Allocator, class traits>
      bool operator==(const basic_string<charT,Allocator,traits>& lhs,
                      const charT* rhs);
    template<class charT, class Allocator, class traits>
      bool operator!=(const basic_string<charT,Allocator,traits>& lhs,
                      const basic_string<charT,Allocator,traits>& rhs);
    template<class charT, class Allocator, class traits>
      bool operator!=(const charT* lhs,
                      const basic_string<charT,Allocator,traits>& rhs);
    template<class charT, class Allocator, class traits>
      bool operator!=(const basic_string<charT,Allocator,traits>& lhs,
                      const charT* rhs);
    template<class charT, class Allocator, class traits>
      bool operator< (const basic_string<charT,Allocator,traits>& lhs,
                      const basic_string<charT,Allocator,traits>& rhs);
    template<class charT, class Allocator, class traits>
      bool operator< (const basic_string<charT,Allocator,traits>& lhs,
                      const charT* rhs);
    template<class charT, class Allocator, class traits>
      bool operator< (const charT* lhs,
                      const basic_string<charT,Allocator,traits>& rhs);
    template<class charT, class Allocator, class traits>
      bool operator> (const basic_string<charT,Allocator,traits>& lhs,
                      const basic_string<charT,Allocator,traits>& rhs);
    template<class charT, class Allocator, class traits>
      bool operator> (const basic_string<charT,Allocator,traits>& lhs,
                      const charT* rhs);
    template<class charT, class Allocator, class traits>
      bool operator> (const charT* lhs,
                      const basic_string<charT,Allocator,traits>& rhs);

    template<class charT, class Allocator, class traits>
      bool operator<=(const basic_string<charT,Allocator,traits>& lhs,
                      const basic_string<charT,Allocator,traits>& rhs);
    template<class charT, class Allocator, class traits>
      bool operator<=(const basic_string<charT,Allocator,traits>& lhs,
                      const charT* rhs);
    template<class charT, class Allocator, class traits>
      bool operator<=(const charT* lhs,
                      const basic_string<charT,Allocator,traits>& rhs);
    template<class charT, class Allocator, class traits>
      bool operator>=(const basic_string<charT,Allocator,traits>& lhs,
                      const basic_string<charT,Allocator,traits>& rhs);
    template<class charT, class Allocator, class traits>
      bool operator>=(const basic_string<charT,Allocator,traits>& lhs,
                      const charT* rhs);
    template<class charT, class Allocator, class traits>
      bool operator>=(const charT* lhs,
                      const basic_string<charT,Allocator,traits>& rhs);
    template<class charT, class Allocator, class traits>
      basic_istream<charT>&
        operator>>(basic_istream<charT>& is,
                   basic_string<charT,Allocator,traits>& a);
    template<class charT, class Allocator, class traits>
      basic_ostream<charT>&
        operator<<(basic_ostream<charT>& os,
                   const basic_string<charT,Allocator,traits>& a);
  // subclause _lib.string_, string:
    struct string_char_traits<char>;
    typedef basic_string<char> string;
  // subclause _lib.wstring_, wstring:
    struct string_char_traits<wchar_t>;
    typedef basic_string<wchar_t> wstring;
  }

1 In  this  subclause,  we  call the basic character types ``char-like''
  types, and also call the  objects  of  char-like  types  ``char-like''
  objects or simply ``character''s.

2 The  header  <string>  defines  a  basic string class template and its
  traits that can handle all ``char-like'' template arguments with  sev­
  eral  function signatures for manipulating varying-length sequences of
  ``char-like'' objects.

3 The header <string> also defines two specific template classes  string
  and wstring and their special traits.

  21.1.1  Template class basic_string              [lib.template.string]

  21.1.1.1  Template class                      [lib.string.char.traits]
       string_char_traits
  namespace std {
    template<class charT> struct string_char_traits {
      typedef charT char_type; // for users to acquire the basic character type

      // constraints
      static void assign(char_type& c1, const char_type& c2)
      static bool eq(const char_type& c1, const char_type& c2)
      static bool ne(const char_type& c1, const char_type& c2)
      static bool lt(const char_type& c1, const char_type& c2)
      static char_type eos(); // the null character
      static basic_istream<charT>&
        char_in(basic_istream<charT>& is, charT& a);
      static basic_ostream<charT>&
        char_out(basic_ostream<charT>& os, charT a);
      static bool is_del(charT a);
        // characteristic function for delimiters of charT
      // speed-up functions
      static int compare(const char_type* s1, const char_type* s2,
                         size_t n);
      static size_t length(const char_type* s);
      static char_type* copy(char_type* s1, const char_type* s2, size_t n);
    };
  }

  21.1.1.2  string_char_traits          [lib.string.char.traits.members]
       members

1 Default definitions.

  21.1.1.2.1  assign                           [lib.char.traits::assign]

  static void assign(char_type& c1, const char_type& c2)

  Effects:
    Assigns c2 to c1.

  21.1.1.2.2  eq                                   [lib.char.traits::eq]

  static bool eq(const char_type& c1, const char_type& c2)

  Returns
    c1 == c2

  21.1.1.2.3  ne                                   [lib.char.traits::ne]

  static bool ne(const char_type& c1, const char_type& c2)

  Returns:
    !(c1 == c2)

  21.1.1.2.4  lt                                   [lib.char.traits::lt]

  static bool lt(const char_type& c1, const char_type& c2)

  Returns:
    c1 < c2

  21.1.1.2.5  eos                                 [lib.char.traits::eos]

  static char_type eos();

  Returns
    The null character, char_type()

  21.1.1.2.6  char_in                         [lib.char.traits::char.in]

  static basic_istream<charT>&
    char_in(basic_istream<charT>& is, charT& a);

  Effects:
    Extracts a charT object.
  Returns:
    is >> a

  21.1.1.2.7  char_out                       [lib.char.traits::char.out]

  static basic_ostream<charT>&
    char_out(basic_ostream<charT>& os, charT a);

  Effects:
    Inserts a charT object.
  Returns:
    os << a

  21.1.1.2.8  is_del                           [lib.char.traits::is.del]

  static bool is_del(charT a);

  Effects:
    Characteristic function for delimiters of charT.
  Returns:
    isspace(a)

  21.1.1.2.9  compare                         [lib.char.traits::compare]

  static int compare(const char_type* s1, const char_type* s2,
                     size_t n);

  Effects:
        for (size_t i = 0; i < n; ++i, ++s1, ++s2)
          if (ne(*s1, *s2)) {
            return lt(*s1, *s2) ? -1 : 1;
          }
        return 0;

  21.1.1.2.10  length                          [lib.char.traits::length]

  static size_t length(const char_type* s);

  Effects:

        size_t l = 0;
        while (ne(*s++, eos()) ++l;
          return l;

  21.1.1.2.11  copy                              [lib.char.traits::copy]

  static char_type* copy(char_type* s1, const char_type* s2, size_t n);

  Effects:
        char_type* s = s1;
        for (size_t i = 0; i < n; ++i) assign(*++s1, *++s2);
        return s;

  21.1.1.3  Template class basic_string               [lib.basic.string]
  namespace std {
    template<class charT, class Allocator = allocator,
             class traits = string_char_traits<charT> >
    class basic_string {
    public:
    // typedefs:
      typedef traits            traits_type;
      typedef traits::char_type value_type;
      typedef value_type*       iterator;
      typedef value_type* const const_iterator;
      typedef allocator::size_type       size_type;
      typedef allocator::difference_type difference_type;
  // Added to make the typedefs work:
      typedef allocator::types<charT> alloc_type;
      typedef alloc_type::reference       reference;
      typedef alloc_type::const_reference const_reference;
      typedef alloc_type::pointer         pointer;
      typedef alloc_type::const_pointer   pointer;
      basic_string();
      basic_string(const basic_string& str, size_type pos = 0,
                   size_type n = NPOS);
      basic_string(const_pointer s, size_type n);
      basic_string(const_pointer s);
      basic_string(size_type n, charT c);
     ~basic_string();
      basic_string& operator=(const basic_string& str);
      basic_string& operator=(const_pointer s);
      basic_string& operator=(charT c);
      basic_string& operator+=(const basic_string& rhs);
      basic_string& operator+=(const_pointer s);
      basic_string& operator+=(charT c);
      basic_string& append(const basic_string& str, size_type pos = 0,
                           size_type n = NPOS);
      basic_string& append(const_pointer s, size_type n);
      basic_string& append(const_pointer s);
      basic_string& append(size_type pos, size_type n, const charT c = charT());

      basic_string& assign(const basic_string& str, size_type pos = 0,
                           size_type n = NPOS);
      basic_string& assign(const_pointer s, size_type n);
      basic_string& assign(const_pointer s);
      basic_string& assign(size_type pos, size_type n, const charT c = charT());
      basic_string& insert(size_type pos1, const basic_string& str,
                           size_type pos2 = 0, size_type n = NPOS);
      basic_string& insert(size_type pos, const_pointer s, size_type n);
      basic_string& insert(size_type pos, const_pointer s);
      basic_string& insert(size_type pos, size_type n, const charT c = charT() );
      basic_string& remove(size_type pos = 0, size_type n = NPOS);
      basic_string& replace(size_type pos1, size_type n1, const basic_string& str,
                            size_type pos2 = 0, size_type n2 = NPOS);
      basic_string& replace(size_type pos, size_type n1, const_pointer s,
                            size_type n2);
      basic_string& replace(size_type pos, size_type n1, const_pointer s);
      basic_string& replace(size_type pos, size_type n, charT c = charT());
      charT     operator[](size_type pos) const;
      reference operator[](size_type pos);
      const_reference at(size_type n) const;
      reference       at(size_type n);
      const_pointer c_str() const;
      const_pointer data() const;
      size_type size() const;
      size_type max_size() const;
      void resize(size_type n, charT c);
      void resize(size_type n);
      size_type capacity() const;
      void reserve(size_type res_arg);
      bool empty() const;
      size_type copy(pointer s, size_type n, size_type pos = 0);
      void swap(basic_string<charT,Allocator,traits>&);
      size_type find(const basic_string& str, size_type pos = 0) const;
      size_type find(const_pointer s, size_type pos, size_type n) const;
      size_type find(const_pointer s, size_type pos = 0) const;
      size_type find(charT c, size_type pos = 0) const;
      size_type rfind(const basic_string& str, size_type pos = NPOS) const;
      size_type rfind(const_pointer s, size_type pos, size_type n) const;
      size_type rfind(const_pointer s, size_type pos = NPOS) const;
      size_type rfind(charT c, size_type pos = NPOS) const;
      size_type find_first_of(const basic_string& str, size_type pos = 0) const;
      size_type find_first_of(const_pointer s, size_type pos, size_type n) const;
      size_type find_first_of(const_pointer s, size_type pos = 0) const;
      size_type find_first_of(charT c, size_type pos = 0) const;
      size_type find_last_of (const basic_string& str, size_type pos = NPOS) const;
      size_type find_last_of (const_pointer s, size_type pos, size_type n) const;
      size_type find_last_of (const_pointer s, size_type pos = NPOS) const;
      size_type find_last_of (charT c, size_type pos = NPOS) const;

      size_type find_first_not_of(const basic_string& str, size_type pos = 0) const;
      size_type find_first_not_of(const_pointer s, size_type pos,
                                  size_type n) const;
      size_type find_first_not_of(const_pointer s, size_type pos = 0) const;
      size_type find_first_not_of(charT c, size_type pos = 0) const;
      size_type find_last_not_of (const basic_string& str, size_type pos = NPOS) const;
      size_type find_last_not_of (const_pointer s, size_type pos,
                                  size_type n) const;
      size_type find_last_not_of (const_pointer s, size_type pos = NPOS) const;
      size_type find_last_not_of (charT c, size_type pos = NPOS) const;
      basic_string substr(size_type pos = 0, size_type n = NPOS) const;
      int compare(const basic_string& str, size_type pos = 0,
                  size_type n = NPOS) const;
      int compare(pointer s, size_type pos, size_type n) const;
      int compare(pointer s, size_type pos = 0) const;
    };
  }

1 For  a char-like type charT, the template class basic_string describes
  objects that can store a sequence consisting of a  varying  number  of
  arbitrary  char-like objects.  The first element of the sequence is at
  position zero.  Such a sequence is also called  a  ``string''  if  the
  given  char-like  type  is  clear  from  context.  In the rest of this
  clause, charT denotes a such given char-like type.   Storage  for  the
  string  is allocated and freed as necessary by the member functions of
  class basic_string.

2 In all cases, size() <= capacity().

3 The functions described in this clause can report two kinds of errors,
  each associated with a distinct exception:

  --a length error is associated with exceptions of type length_error;

  --an   out-of-range  error  is  associated  with  exceptions  of  type
    out_of_range .

  21.1.1.4  basic_string member functions           [lib.string.members]

  21.1.1.4.1  basic_string constructors                [lib.string.cons]

  basic_string();

  Effects:
    Constructs an object of class basic_string.  The  postconditions  of
    this function are indicated in Table 2:

                      Table 2--basic_string() effects

                    +----------------------------------+
                    | Element            Value         |
                    +----------------------------------+
                    |data()       an unspecified value |
                    |size()       0                    |
                    |capacity()   an unspecified value |
                    +----------------------------------+

    basic_string(const basic_string<charT,Allocator,traits>& str,
                 size_type pos = 0, size_type n = NPOS);

  Requires:
    pos <= size()
  Throws:
    out_of_range if pos > str .size().
  Effects:
    Constructs an object of class basic_string and determines the effec­
    tive length rlen of the initial string value as the smaller of n and
    str .size() - pos, as indicated in Table 3:

      Table 3--basic_string(basic_string,size_type,size_type) effects

              +----------------------------------------------+
              | Element                  Value               |
              +----------------------------------------------+
              |data()       points  at  the first element of |
              |             an allocated copy of  rlen  ele­ |
              |             ments  of  the string controlled |
              |             by str beginning at position pos |
              |size()       rlen                             |
              |capacity()   a value at least as large as len |
              +----------------------------------------------+

    basic_string(const_pointer s, size_type n = NPOS);

  Requires:
    s  shall  not  be  a  null pointer.
  Effects:
    Constructs an object  of  class basic_string and determines its ini­
    tial string value from the array of charT of length  n  whose  first
    element is designated  by  s, as indicated in Table 4:

           Table 4--basic_string(const_pointer,size_type) effects

              +----------------------------------------------+
              | Element                  Value               |
              +----------------------------------------------+
              |data()       points  at  the first element of |
              |             an allocated copy of  the  array |
              |             whose  first  element is pointed |
              |             at by s                          |
              |size()       n                                |
              |capacity()   a value at least as large as len |
              +----------------------------------------------+

    basic_string(const_pointer s);

  Requires:
    s shall not be a null pointer.
  Effects:
    Constructs an object of class basic_string and determines  its  ini­
    tial   string   value   from   the   array   of   charT   of  length
    traits::length(s) whose first element is designated by  s, as  indi­
    cated in Table 5:

                Table 5--basic_string(const_pointer) effects

              +----------------------------------------------+
              | Element                  Value               |
              +----------------------------------------------+
              |data()       points  at  the first element of |
              |             an allocated copy of  the  array |
              |             whose  first  element is pointed |
              |             at by s                          |
              |size()       traits::length(s)                |
              |capacity()   a value at least as large as len |
              +----------------------------------------------+
  Notes:
    Uses traits::length().

    basic_string(size_type n, charT c);

  Requires:
    n < NPOS
  Throws:
    length_error if n  == NPOS.
  Effects:
    Constructs an object of class basic_string and determines  its  ini­
    tial string value by repeating the char-like object c for all n ele­
    ments, as indicated in Table 6:

               Table 6--basic_string(charT,size_type) effects

              +----------------------------------------------+
              | Element                  Value               |
              +----------------------------------------------+
              |data()       points at the first  element  of |
              |             an  allocated  array  of  n ele­ |
              |             ments, each storing the  initial |
              |             value c                          |
              |size()       n                                |
              |capacity()   a value at least as large as len |
              +----------------------------------------------+

  21.1.1.4.2  basic_string::operator=                  [lib.string::op=]

  basic_string<charT,Allocator,traits>&
    operator=(const basic_string<charT,Allocator,traits>& str);

  Returns:
    *this = basic_string<charT,Allocator,traits>(str).

    basic_string<charT,Allocator,traits>&
      operator=(const_pointer s);

  Returns:
    *this = basic_string<charT,Allocator,traits>(s).
  Notes:
    Uses traits::length().

    basic_string<charT,Allocator,traits>& operator=(charT c);

  Returns:
    *this = basic_string<charT,Allocator,traits>(c).

  21.1.1.4.3  basic_string::operator+=                [lib.string::op+=]

  basic_string<charT,Allocator,traits>&
    operator+=(const basic_string<charT,Allocator,traits>& rhs);

  Returns:
    append(rhs).

    basic_string<charT,Allocator,traits>& operator+=(const_pointer s);

  Returns:
    *this += basic_string<charT,Allocator,traits>(s).
  Notes:
    Uses traits::length().

    basic_string<charT,Allocator,traits>& operator+=(charT c);

  Returns:
    *this += basic_string<charT,Allocator,traits>(c).

  21.1.1.4.4  basic_string::append                  [lib.string::append]

  basic_string<charT,Allocator,traits>&
    append(const basic_string<charT,traits>& str,
           size_type pos = 0, size_type n = NPOS);

  Requires:
    pos  <= size()
  Throws:
    out_of_range if pos  > str .size().
  Effects:
    Determines  the effective length rlen of the string to append as the
    smaller of n and str  .size()  -  pos.   The  function  then  throws
    length_error if size() >= NPOS - rlen.
    Otherwise, the function replaces the string controlled by *this with
    a string of length size() + rlen whose first len elements are a copy
    of  the original string controlled by *this and whose remaining ele­
    ments are a copy of the initial elements of the string controlled by
    str beginning at position pos.
  Returns:
    *this.

    basic_string<charT,Allocator,traits>&
      append(const_pointer s, size_type n);

  Returns:
    append(basic_string<charT,Allocator,traits>(s,n)).

    basic_string<charT,Allocator,traits>& append(const_pointer s);

  Returns:
    append(basic_string<charT,Allocator,traits>(s)).
  Notes:
    Uses traits::length().

    basic_string<charT,Allocator,traits>&
      append(size_type pos, size_type n, const charT c = charT());

  Returns:
    append(basic_string<charT,Allocator,traits>(c,n),pos).

  21.1.1.4.5  basic_string::assign                  [lib.string::assign]

  basic_string<charT,Allocator,traits>&
    assign(const basic_string<charT,traits>& str,
           size_type pos = 0, size_type n = NPOS);

  Requires:
    pos  <= size()
  Throws:
    out_of_range if pos  > str .size().

  Effects:
    Determines  the effective length rlen of the string to assign as the
    smaller of n and str .size() - pos.
    The function then replaces the string controlled  by  *this  with  a
    string  of  length rlen whose elements are a copy of the string con­
    trolled by str beginning at position pos.
  Returns:
    *this.

    basic_string<charT,Allocator,traits>&
      assign(const_pointer s, size_type n);

  Returns:
    assign(basic_string<charT,Allocator,traits>(s,n)).

    basic_string<charT,Allocator,traits>& assign(const_pointer s);

  Returns:
    assign(basic_string(s)).
  Notes:
    Uses traits::length().

    basic_string<charT,Allocator,traits>&
      assign(size_type pos, size_type n, const charT c = charT());

  Returns:
    assign(basic_string<charT,Allocator,traits>(c,n),pos).

  21.1.1.4.6  basic_string::insert                  [lib.string::insert]

  basic_string<charT,Allocator,traits>&
    insert(size_type pos1,
           const basic_string<charT,Allocator,traits>& str,
           size_type pos2 = 0, size_type n = NPOS);

  Requires
    pos1  <= size()
  Throws:
    out_of_range if pos1  > size() or pos2  > str .size().
  Effects:
    Determines the effective length rlen of the string to insert as  the
    smaller  of  n  and  str  .len  - pos2.  Then throws length_error if
    size() >= NPOS - rlen.
    Otherwise, the function replaces the string controlled by *this with
    a  string  of  length  size() + rlen whose first pos1 elements are a
    copy of the initial elements of the original  string  controlled  by
    *this,  whose  next  rlen elements are a copy of the elements of the
    string controlled by str  beginning  at  position  pos2,  and  whose
    remaining elements are a copy of the remaining elements of the orig­
    inal string controlled by *this.
  Returns:
    *this.

    basic_string<charT,Allocator,traits>&
      insert(size_type pos, const_pointer s, size_type n);

  Returns:
    insert(pos,basic_string<charT,Allocator,traits>(s,n)).

    basic_string<charT,Allocator,traits>&
      insert(size_type pos, const_pointer s);

  Returns:
    insert(pos,basic_string(s)).
  Notes:
    Uses traits::length().

    basic_string<charT,Allocator,traits>&
      insert(size_type pos, size_type n, const charT c = charT());

  Returns:
    insert(pos,basic_string<charT,Allocator,traits>(c,n)).

  21.1.1.4.7  basic_string::remove                  [lib.string::remove]

  basic_string<charT,Allocator,traits>&
    remove(size_type pos = 0, size_type n = NPOS);

  Requires:
    pos  <= size()
  Throws:
    out_of_range if pos  > size().
  Effects:
    Determines the effective length xlen of the string to be removed  as
    the smaller of n and size() - pos.
    The  function  then  replaces  the string controlled by *this with a
    string of length size() - xlen whose first pos elements are  a  copy
    of  the initial elements of the original string controlled by *this,
    and whose remaining elements are a copy of the elements of the orig­
    inal string controlled by *this beginning at position pos + xlen.
  Returns:
    *this.

  21.1.1.4.8  basic_string::replace                [lib.string::replace]

  basic_string<charT,Allocator,traits>&
    replace(size_type pos1, size_type n1,
            const basic_string<charT,Allocator,traits>& str,
            size_type pos2 = 0, size_type n2 = NPOS);

  Requires:
    pos1  <= size() && pos2  <= size().
  Throws:
    out_of_range if pos1  > size() or pos2  > str .size().
  Effects:
    Determines  the effective length xlen of the string to be removed as

    the smaller of n1 and size() - &pos1.  It also determines the effec­
    tive  length  rlen of the string to be inserted as the smaller of n2
    and str .size() - pos2.  Then throws length_error if size() - xlen
    >= NPOS - rlen.
    Otherwise, the function replaces the string controlled by *this with
    a string of length size() - xlen whose first  pos1  elements  are  a
    copy  of  the  initial elements of the original string controlled by
    *this, whose next rlen elements are a copy of the  initial  elements
    of  the  string  controlled  by  str beginning at position pos2, and
    whose remaining elements are a copy of the elements of the  original
    string controlled by *this beginning at position pos1 + xlen.
  Returns:
    *this.

    basic_string<charT,Allocator,traits>&
      replace(size_type pos, size_type n1, const_pointer s, size_type n2);

  Returns:
    replace(pos,n1,basic_string<charT,Allocator,traits>(s,n2)).

    basic_string<charT,Allocator,traits>&
      replace(size_type pos, size_type n1, const_pointer s);

  Returns:
    replace(pos,n1,basic_string<charT,Allocator,traits>(s)).
  Notes:
    Uses traits::length().

    basic_string<charT,Allocator,traits>&
      replace(size_type pos, size_type n, charT c = charT());

  Returns:
    replace(pos,n,basic_string<charT,Allocator,traits>(c,n)).

  21.1.1.4.9  basic_string::operator[]            [lib.string::op.array]

  charT     operator[](size_type pos) const;
  reference operator[](size_type pos);

  Returns:
    If  pos    <  size(),  returns  data()[pos ].  Otherwise, if pos  ==
    size(), the const version  returns  traits::eos().   Otherwise,  the
    behavior is undefined.
  Notes:
    The  reference  returned  by the non- const version is invalid after
    any subsequent call to c_str(), data(), or  any  non-  const  member
    function for the object.

  21.1.1.4.10  basic_string::at                         [lib.string::at]

  const_reference at(size_type n) const;
  reference       at(size_type n);

  Requires:
    pos < size()
  Throws:
    out_of_range if pos  >= size().
  Returns:
    operator[](pos ).

  +-------                 BEGIN BOX 1                -------+
  Previous  definition  of put_at(): Otherwise, if pos == len, the func­
  tion replaces the string controlled by *this with a string  of  length
  len + 1 whose first len elements are a copy of the original string and
  whose remaining element is initialized to c.  Otherwise, the  function
  assigns c to ptr[pos].
  +-------                  END BOX 1                 -------+

  21.1.1.4.11  basic_string::c_str                   [lib.string::c.str]

  const charT* c_str() const;

  Returns:
    A  pointer  to  the initial element of an array of length size() + 1
    whose first size() elements equal the corresponding elements of  the
    string  controlled by *this and whose last element is a null charac­
    ter specified by traits::eos().
  Requires:
    The program shall not alter any of the values stored in  the  array.
    Nor  shall  the  program treat the returned value as a valid pointer
    value after any subsequent call to a non-const  member  function  of
    the class basic_string that designates the same object as this.
  Notes:
    Uses traits::eos().

  21.1.1.4.12  basic_string::data                     [lib.string::data]

  const charT* data() const;

  Returns:
    c_str() if size() is nonzero, otherwise a null pointer.
  Requires:
    The  program shall not alter any of the values stored in the charac­
    ter array.  Nor shall the program treat  the  returned  value  as  a
    valid pointer value after any subsequent call to a non- const member
    function of basic_string that designates the same object as this.

  21.1.1.4.13  basic_string::size                     [lib.string::size]

  size_type size() const:

  Returns:
    a count of the number of char-like objects currently in the  string.
  Notes:
    Uses traits::length().

  21.1.1.4.14  basic_string::max_size             [lib.string::max.size]

  size_type max_size() const:

  Returns:
    The maximum size of the string.

  21.1.1.4.15  basic_string::resize                 [lib.string::resize]

  void resize(size_type n, charT c);

  Requires:
    n  != NPOS
  Throws:
    length_error if n  == NPOS.
  Effects:
    Alters the length of the string designated by *this as follows:

  --If  n    <=  size(),  the function replaces the string designated by
    *this with a string of length n whose elements are  a  copy  of  the
    initial elements of the original string designated by *this.

  --If n  > size(), the function replaces the string designated by *this
    with a string of length n whose first size() elements are a copy  of
    the  original  string  designated by *this, and whose remaining ele­
    ments are all initialized to c.

    void resize(size_type n);

  Returns:
    resize(n, eos()).
  Notes:
    Uses traits::eos().

  21.1.1.4.16  basic_string::reserve               [lib.string::reserve]

  size_type capacity() const;

  Returns:
    the size of the allocated storage in the string.

    void reserve(size_type res_arg);

1 The  member  function  reserve()  is  a  directive  that   informs   a
  basic_string  of  a  planned change in size, so that it can manage the
  storage allocation accordingly.
  Effects:
    After reserve(), capacity() is greater or equal to the  argument  of
    reserve  if reallocation happens; and equal to the previous value of
    capacity() otherwise.
    Reallocation happens at this point if and only if the current capac­
    ity is less than the argument of reserve().

  Complexity:
    It does not change the size of the sequence and takes at most linear
    time in the size of the sequence.
  Notes:
    Reallocation invalidates all the references, pointers, and iterators
    referring to the elements in the sequence.  It is guaranteed that no
    reallocation takes place during the  insertions  that  happen  after
    reserve()  takes  place  till  the  time when the size of the string
    reaches the size specified by reserve().

  21.1.1.4.17  basic_string::empty                   [lib.string::empty]

  bool empty() const;

  Returns:
    size() == 0.

  21.1.1.4.18  basic_string::copy                     [lib.string::copy]

  size_type copy(pointer s, size_type n, size_type pos = 0);

  Requires:
    pos  <= size()
  Throws:
    out_of_range if pos  > size().
  Effects:
    Determines the effective length rlen of the string to  copy  as  the
    smaller  of  n  and  size() - pos.  s shall designate an array of at
    least rlen elements.
    The function then replaces the string designated by s with a  string
    of length rlen whose elements are a copy of the string controlled by
    *this beginning at position pos.1)
  Returns:
    rlen.

  21.1.1.4.19  basic_string::swap                     [lib.string::swap]

  void swap(basic_string<charT,Allocator,traits>& s);

  Effects:
    Swaps the contents of the two strings.
  Postcondition:
    *this contains the characters that were in s, s contains the charac­
    ters that were in *this.
  Complexity:
    Constant time.

  _________________________
  1) The function does not append a null object to the string.

  21.1.1.4.20  basic_string::find                     [lib.string::find]

  size_type find(const basic_string<charT,Allocator,traits>& str,
                 size_type pos = 0) const;

  Effects:
    Determines  the lowest position xpos, if possible, such that both of
    the following conditions obtain:

  --pos <= xpos and xpos  + str.size() <= size();

  --traits::eq(at(xpos+I),str.at(I)) for all elements I  of  the  string
    controlled by str.
  Returns:
    xpos  if  the  function can determine such a value for xpos.  Other­
    wise, returns NPOS.

    size_type find(const_pointer s, size_type pos, size_type n) const;

  Returns:
    find(basic_string<charT,Allocator,tratis>(s,n)pos).

    size_type find(const_pointer s, size_type pos = 0) const;

  Returns:
    find(basic_string<charT,Allocator,traits>(s),pos).
  Notes:
    Uses traits::length().

    size_type find(charT c, size_type pos = 0) const;

  Returns:
    find(basic_string<charT,Allocator,traits>(c),pos).

  21.1.1.4.21  basic_string::rfind                           [lib.rfind]

  size_type rfind(const basic_string<charT,Allocator,traits>& str,
                  size_type pos = NPOS) const;

  Effects:
    Determines the highest position xpos, if possible, such that both of
    the following conditions obtain:

  --xpos <= pos and xpos  + &str .size() <= size();

  --traits::eq(at(xpos+I),str.at(I))  for  all  elements I of the string
    controlled by str.
  Returns:
    xpos if the function can determine such a value  for  xpos.   Other­
    wise, returns NPOS.

    size_type rfind(const_pointer s, size_type pos, size_type n) const;

  Returns:
    rfind(basic_string<charT,Allocator,traits>(s,n),pos).

    size_type rfind(const_pointer s, size_type pos = NPOS) const;

  Returns:
    rfind(basic_string<charT,Allocator,traits>(s),pos).
  Notes:
    Uses traits::length().

    size_type rfind(charT c, size_type pos = NPOS) const;

  Returns:
    rfind(basic_string<charT,Allocator,traits>(c,n),pos).

  21.1.1.4.22                                [lib.string::find.first.of]
       basic_string::find_first_of

  size_type
    find_first_of(const basic_string<charT,Allocator,traits>& str,
                  size_type pos = 0) const;

  Effects:
    Determines the lowest position xpos, if possible, such that both  of
    the following conditions obtain:

  --pos <= xpos and xpos  < size();

  --traits::eq(at(xpos),  str.at(I))  for  some  element I of the string
    controlled by str.
  Returns:
    xpos if the function can determine such a value  for  xpos.   Other­
    wise, returns NPOS.

    size_type
      find_first_of(const_pointer s, size_type pos, size_type n) const;

  Returns:
    find_first_of(basic_string<charT,Allocator,tratis>(s,n),pos).

    size_type find_first_of(const_pointer s, size_type pos = 0) const;

  Returns:
    find_first_of(basic_string<charT,Allocator,tratis>(s),pos).
  Notes:
    Uses traits::length().

    size_type find_first_of(charT c, size_type pos = 0) const;

  Returns:
    find_first_of(basic_string<charT,Allocator,tratis>(c),pos).

  21.1.1.4.23                                 [lib.string::find.last.of]
       basic_string::find_last_of

  size_type
    find_last_of(const basic_string<charT,Allocator,traits>& str,
                 size_type pos = NPOS) const;

  Effects:
    Determines the highest position xpos, if possible, such that both of
    the following conditions obtain:

  --xpos <= pos and pos  < size();

  --traits::eq(at(xpos),str.at(I)) for some element I of the string con­
    trolled by str.
  Returns:
    xpos if the function can determine such a value  for  xpos.   Other­
    wise, returns NPOS.

    size_type find_last_of(const_pointer s, size_type pos, size_type n) const;

  Returns:
    find_last_of(basic_string<charT,Allocator,tratis>(s,n),pos).

    size_type find_last_of(const_pointer s, size_type pos = NPOS) const;

  Returns:
    find_last_of(basic_string<charT,Allocator,tratis>(s),pos).
  Notes:
    Uses traits::length().

    size_type find_last_of(charT c, size_type pos = NPOS) const;

  Returns:
    find_last_of(basic_string<charT,Allocator,traits>(c),pos).

  21.1.1.4.24                            [lib.string::find.first.not.of]
       basic_string::find_first_not_of

  size_type
    find_first_not_of(const basic_string<charT,Allocator,traits>& str,
                      size_type pos = 0) const;

  Effects:
    Determines  the lowest position xpos, if possible, such that both of
    the following conditions obtain:

  --pos <= xpos and xpos  < size();

  --traits::eq(at(xpos), str.at(I)) for no element I of the string  con­
    trolled by str.
  Returns:
    xpos   if  the  function  can  determine  such  a  value  for  xpos.

    Otherwise, returns NPOS.

    size_type
      find_first_not_of(const_pointer s, size_type pos, size_type n) const;

  Returns:
    find_first_not_of(basic_string<charT,Allocator,traits>(s,n),pos).

    size_type find_first_not_of(const_pointer s, size_type pos = 0) const;

  Returns:
    find_first_not_of(basic_string<charT,Allocator,traits>(s),pos).
  Notes:
    Uses traits::length().

    size_type find_first_not_of(charT, size_type pos = 0) const;

  Returns:
    find_first_not_of(basic_string<charT,Allocator,tratis>(c),pos).

  21.1.1.4.25                             [lib.string::find.last.not.of]
       basic_string::find_last_not_of

  size_type
    find_last_not_of(const basic_string<charT,Allocator,traits>& str,
                     size_type pos = NPOS) const;

  Effects:
    Determines the highest position xpos, if possible, such that both of
    the following conditions obtain:

  --xpos <= pos and pos  < size();

  --traits::eq(at(xpos),  str.at(I)) for no element I of the string con­
    trolled by str.
  Returns:
    xpos if the function can determine such a value  for  xpos.   Other­
    wise, returns NPOS.

    size_type find_last_not_of(const_pointer s, size_type pos, size_type n) const;

  Returns:
    find_last_not_of(basic_string<charT,Allocator,traits>(s,n),pos).

    size_type find_last_not_of(const_pointer s, size_type pos = NPOS) const;

  Returns:
    find_last_not_of(basic_string<charT,Allocator,traits>(s),pos).
  Notes:
    Uses traits::length().

    size_type find_last_not_of(charT c, size_type pos = NPOS) const;

  Returns:
    find_last_not_of(basic_string<charT,Allocator,traits>(c),pos).

  21.1.1.4.26  basic_string::substr                 [lib.string::substr]

  basic_string<charT,Allocator,traits>
    substr(size_type pos = 0, size_type n = NPOS) const;

  Requires:
    pos  <= size()
  Throws:
    out_of_range if pos  > size().
  Effects:
    Determines  the  effective  length rlen of the string to copy as the
    smaller of n and size() - pos.
  Returns:
    basic_string<charT,Allocator,traits>(data()+pos,rlen).

  21.1.1.4.27  basic_string::compare               [lib.string::compare]

  int compare(const basic_string<charT,Allocator,traits>& str,
                  size_type pos = 0, size_type n = NPOS)

  Requires:
    pos  <= size()
  Throws:
    out_of_range if pos  > size().
  Effects:
    Determines the effective length rlen of the strings  to  compare  as
    the smallest of n, size() - pos, and str .size().  The function then
    compares       the       two        strings        by        calling
    traits::compare(data()+pos,str.data(),rlen).
  Returns:
    the nonzero result if the result of the comparison is nonzero.  Oth­
    erwise, returns a value as indicated in Table 7:

                         Table 7--compare() results

                +------------------------------------------+
                |        Condition            Return Value |
                +------------------------------------------+
                |size() - pos <  str.size()   a value < 0  |
                |size() - pos == str.size()   0            |
                |size() - pos >  str.size()   a value > 0  |
                +------------------------------------------+

1 Uses traits::compare().

  int compare(const_pointer s, size_type pos, size_type n) const;

  Returns:
    compare(basic_string<charT,Allocator,traits>(s, n), pos).
  Notes:
    Uses traits::compare().

    int compare(const_pointer s, size_type pos = 0) const;

  Returns:
    compare(basic_string<charT,Allocator,traits>(s), pos).
  Notes:
    Uses traits::length() and traits::compare().

  21.1.1.5  basic_string non-member              [lib.string.nonmembers]
       functions

  21.1.1.5.1  operator+                                [lib.string::op+]

  template<class charT, class Allocator, class traits>
    basic_string<charT,Allocator,traits>
      operator+(const basic_string<charT,Allocator,traits>& lhs,
                const basic_string<charT,Allocator,traits>& rhs);

  Returns:
    basic_string<charT,Allocator,traits>(lhs).append(rhs).

    template<class charT, class Allocator, class traits>
      basic_string<charT,Allocator,traits>
        operator+(const_pointer lhs,
                  const basic_string<charT,Allocator,traits>& rhs);

  Returns:
    basic_string<charT,Allocator,traits>(lhs) + rhs.
  Notes:
    Uses traits::length().

    template<class charT, class Allocator, class traits>
      basic_string<charT,Allocator,traits>
        operator+(charT lhs,
                  const basic_string<charT,Allocator,traits>& rhs);

  Returns:
    basic_string<charT,Allocator,traits>(lhs)+rhs.

    template<class charT, class Allocator, class traits>
      basic_string<charT,Allocator,traits>
        operator+(const basic_string<charT,Allocator,traits>& lhs,
                  const_pointer rhs);

  Returns:
    basic_string<charT,Allocator,tratis>(lhs)+
    basic_string<charT,Allocator,tratis>(rhs).
  Notes:
    Uses traits::length().

    template<class charT, class Allocator, class traits>
      basic_string<charT,Allocator,traits>
        operator+(const basic_string<charT,Allocator,traits>& lhs,
                  charT rhs);

  Returns:
    lhs  + basic_string<charT,Allocator,traits>(rhs).

  21.1.1.5.2  operator==                        [lib.string::operator==]

  template<class charT, class Allocator, class traits>
    bool operator==(const basic_string<charT,Allocator,traits>& lhs,
                    const basic_string<charT,Allocator,traits>& rhs);

  Returns:
    lhs .compare(rhs) == 0.

    template<class charT, class Allocator, class traits>
      bool operator==(const charT* lhs,
                      const basic_string<charT,Allocator,traits>& rhs);

  Returns:
    basic_string<charT,Allocator,tratis>(lhs) == rhs.

    template<class charT, class Allocator, class traits>
      bool operator==(const basic_string<charT,Allocator,traits>& lhs,
                      const charT* rhs);

  Returns:
    lhs  == basic_string<charT,Allocator,traits>(rhs).
  Notes:
    Uses traits::length().

  21.1.1.5.3  operator!=                              [lib.string::op!=]

  template<class charT, class Allocator, class traits>
    bool operator!=(const basic_string<charT,Allocator,traits>& lhs,
                    const basic_string<charT,Allocator,traits>& rhs);

  template<class charT, class Allocator, class traits>
    bool operator!=(const charT* lhs,
                    const basic_string<charT,Allocator,traits>& rhs);

  template<class charT, class Allocator, class traits>
    bool operator!=(const basic_string<charT,Allocator,traits>& lhs,
                    const charT* rhs);

  Returns:
    basic_string<charT,Allocator,traits>(lhs).compare(rhs) != 0.
  Notes:
    Uses traits::length().

  21.1.1.5.4  operator<                                [lib.string::op<]

  template<class charT, class Allocator, class traits>
    bool operator< (const basic_string<charT,Allocator,traits>& lhs,
                    const basic_string<charT,Allocator,traits>& rhs);

  template<class charT, class Allocator, class traits>
    bool operator< (const basic_string<charT,Allocator,traits>& lhs,
                    const charT* rhs);

  template<class charT, class Allocator, class traits>
    bool operator< (const charT* lhs,
                    const basic_string<charT,Allocator,traits>& rhs);

  Returns:
    basic_string<charT,Allocator,traits>(f6lhs).compare(rhs) < 0.

  21.1.1.5.5  operator>                                [lib.string::op>]

  template<class charT, class Allocator, class traits>
    bool operator> (const basic_string<charT,Allocator,traits>& lhs,
                    const basic_string<charT,Allocator,traits>& rhs);

  template<class charT, class Allocator, class traits>
    bool operator> (const basic_string<charT,Allocator,traits>& lhs,
                    const charT* rhs);

  template<class charT, class Allocator, class traits>
    bool operator> (const charT* lhs,
                    const basic_string<charT,Allocator,traits>& rhs);

  Returns:
    basic_string<charT,Allocator,traits>(f6lhs).compare(rhs) > 0.

  21.1.1.5.6  operator<=                              [lib.string::op<=]

  template<class charT, class Allocator, class traits>
    bool operator<=(const basic_string<charT,Allocator,traits>& lhs,
                    const basic_string<charT,Allocator,traits>& rhs);

  template<class charT, class Allocator, class traits>
    bool operator<=(const basic_string<charT,Allocator,traits>& lhs,
                    const charT* rhs);

  template<class charT, class Allocator, class traits>
    bool operator<=(const charT* lhs,
                    const basic_string<charT,Allocator,traits>& rhs);

  Returns:
    basic_string<charT,Allocator,traits>(f6lhs).compare(rhs) <= 0.

  21.1.1.5.7  operator>=                              [lib.string::op>=]

  template<class charT, class Allocator, class traits>
    bool operator>=(const basic_string<charT,Allocator,traits>& lhs,
                    const basic_string<charT,Allocator,traits>& rhs);

  template<class charT, class Allocator, class traits>
    bool operator>=(const basic_string<charT,Allocator,traits>& lhs,
                    const charT* rhs);

  template<class charT, class Allocator, class traits>
    bool operator>=(const charT* lhs,
                    const basic_string<charT,Allocator,traits>& rhs);

  Returns:
    basic_string<charT,Allocator,traits>(f6lhs).compare(rhs) >= 0.

  21.1.1.5.8  Inserters and extractors

1
    template<class charT, class Allocator, class traits>
      basic_istream<charT>&
        operator>>(basic_istream<charT>& is, basic_string<charT,Allocator,traits>& a);

  Notes:
    Uses traits::char_in and is_del().

    template<class charT, class Allocator, class traits>
      basic_ostream<charT>&
        operator<<(basic_ostream<charT>& os,
                   const basic_string<charT,Allocator,traits>& a);

  Notes:
    Uses traits::char_out().

  21.1.2  Class string                                      [lib.string]
  namespace std {
    struct string_char_traits<char> {
      typedef char char_type;
      static void assign(char_type& c1, const char_type& c2);
      static bool eq(const char_type& c1, const char_type& c2);
      static bool ne(const char_type& c1, const char_type& c2);
      static bool lt(const char_type& c1, const char_type& c2);
      static char_type eos();
      static int compare(const char_type* s1, const char_type* s2,
                         size_type n);
      static size_type length(const char_type* s);
      static char_type* copy(char_type* s1, const char_type* s2, size_type n);
    };

    typedef basic_string<char> string;
  }

  21.1.3  string_char_traits<char>           [lib.string.traits.members]
       members

  21.1.3.1  assign                           [lib.string.traits::assign]

  static void assign(char_type& c1, const char_type& c2);

  Effects:
    c1 = c2

  21.1.3.2  eq                                   [lib.string.traits::eq]

  static bool eq(const char_type& c1, const char_type& c2);

  Returns:
    c1 == c2

  21.1.3.3  ne                                   [lib.string.traits::ne]

  static bool ne(const char_type& c1, const char_type& c2);

  Returns:
    c1 != c2

  21.1.3.4  lt                                   [lib.string.traits::lt]

  static bool lt(const char_type& c1, const char_type& c2);

  Returns:
    c1 < c2

  21.1.3.5  eos                                 [lib.string.traits::eos]

  static char_type eos();

  Returns:
    0

  21.1.3.6  compare                         [lib.string.traits::compare]

  static int compare(const char_type* s1, const char_type* s2,
       size_type n);

  Returns:
    memcmp(s1,s2,n)

  21.1.3.7  length                           [lib.string.traits::length]

  static size_type length(const char_type* s);

  Returns:
    strlen(s)

  21.1.3.8  copy                               [lib.string.traits::copy]

  static char_type* copy(char_type* s1, const char_type* s2, size_type n);

  Returns:
    memcpy(s1,s2,n)

  21.1.4  Class wstring                                    [lib.wstring]
  namespace std {
    struct string_char_traits<wchar_t> {
      typedef wchar_t char_type;
      static void assign(char_type& c1, const char_type& c2);
      static bool eq(const char_type& c1, const char_type& c2);
      static bool ne(const char_type& c1, const char_type& c2);
      static bool lt(const char_type& c1, const char_type& c2);
      static char_type eos();
      static int compare(const char_type* s1, const char_type* s2, size_type n);
      static size_type length(const char_type* s);
      static char_type* copy(char_type* s1, const char_type* s2, size_type n);
    };
    typedef basic_string<wchar_t> wstring;
  }

  21.1.5  string_char_traits<wchar_t> members      [lib.wstring.members]

  21.1.5.1  assign                                 [lib.wstring::assign]

  static void assign(char_type& c1, const char_type& c2);

  Effects:
    c1 = c2

  21.1.5.2  eq                                         [lib.wstring::eq]

  static bool eq(const char_type& c1, const char_type& c2);

  Returns:
    c1 == c2

  21.1.5.3  ne                                         [lib.wstring::ne]

  static bool ne(const char_type& c1, const char_type& c2);

  Returns:
    c1 != c2

  21.1.5.4  lt                                         [lib.wstring::lt]

  static bool lt(const char_type& c1, const char_type& c2);

  Returns:
    c1 < c2

  21.1.5.5  eos                                       [lib.wstring::eos]

  static char_type eos();

  Returns:
    0

  21.1.5.6  compare                               [lib.wstring::compare]

  static int compare(const char_type* s1, const char_type* s2,
                     size_type n);

  Returns:
    wmemcmp(s1,s2,n)

  21.1.5.7  length                                 [lib.wstring::length]

  static size_type length(const char_type* s);

  Returns:
    wcslen(s)

  21.1.5.8  copy                                     [lib.wstring::copy]

  static char_type* copy(char_type* s1, const char_type* s2,
                         size_type n);

  Returns:
    wmemcpy(s1,s2,n)

  21.2  Null-terminated sequence utilities               [lib.c.strings]

1 Headers <cctype>, <cwctype>, <cstring>, <cwchar>, <cstdlib>( multibyte
  conversions), and <ciso646>.

                    Table 7--Header <cctype> synopsis

            +-------------------------------------------------+
            | Type                    Name(s)                 |
            +-------------------------------------------------+
            |Functions:                                       |
            |isalnum   isdigit   isprint   isupper    tolower |
            |isalpha   isgraph   ispunct   isxdigit   toupper |
            |iscntrl   islower   isspace                      |
            +-------------------------------------------------+

                    Table 7--Header <cwctype> synopsis

   +------------------------------------------------------------------+
   |  Type                            Name(s)                         |
   +------------------------------------------------------------------+
   |Macro:     WEOF <cwctype>                                         |
   +------------------------------------------------------------------+
   |Types:     wctrans_t   wctype_t   wint_t <cwctype>                |
   +------------------------------------------------------------------+
   |Functions:                                                        |
   |iswalnum   iswctype    iswlower   iswspace    towctrans   wctrans |
   |iswalpha   iswdigit    iswprint   iswupper    towlower    wctype  |
   |iswcntrl   iswgraph    iswpunct   iswxdigit   towupper            |
   +------------------------------------------------------------------+

                    Table 7--Header <cstring> synopsis

            +-------------------------------------------------+
            | Type                    Name(s)                 |
            +-------------------------------------------------+
            |Macro:    NULL <cstring>                         |
            +-------------------------------------------------+
            |Type:     size_type <cstring>                    |
            +-------------------------------------------------+
            |Functions:                                       |
            |strcoll              strlen    strpbrk   strtok  |
            |strcat    strcpy     strncat   strrchr   strxfrm |
            |strchr    strcspn    strncmp   strspn            |
            |strcmp    strerror   strncpy   strstr            |
            +-------------------------------------------------+

                    Table 7--Header <cwchar> synopsis

  +------------------------------------------------------------------------+
  |  Type                               Name(s)                            |
  +------------------------------------------------------------------------+
  |Macros:    NULL <cwchar>   WCHAR_MAX   WCHAR_MIN   WEOF <cwchar>        |
  +------------------------------------------------------------------------+
  |Types:     mbstate_t       wint_t <cwchar>                              |
  +------------------------------------------------------------------------+
  |Struct:    tm <cwchar>                                                  |
  +------------------------------------------------------------------------+
  |Functions:                                                              |
  |btowc      getwchar        ungetwc     wcscpy      wcsrtombs   wmemchr  |
  |fgetwc     mbrlen          vfwprintf   wcscspn     wcsspn      wmemcmp  |
  |fgetws     mbrtowc         vswprintf   wcsftime    wcsstr      wmemcpy  |
  |fputwc     mbsinit         vwprintf    wcslen      wcstod      wmemmove |
  |fputws     mbsrtowcs       wcrtomb     wcsncat     wcstok      wmemset  |
  |fwide      putwc           wcscat      wcsncmp     wcstol      wprintf  |
  |fwprintf   putwchar        wcschr      wcsncpy     wcstoul     wscanf   |
  |fwscanf    swprintf        wcscmp      wcspbrk     wcsxfrm              |
  |getwc      swscanf         wcscoll     wcsrchr     wctob                |
  +------------------------------------------------------------------------+

                    Table 7--Header <cstdlib> synopsis

                +-----------------------------------------+
                | Type                Name(s)             |
                +-----------------------------------------+
                |Macros:   MB_CUR_MAX                     |
                +-----------------------------------------+
                |Functions:                               |
                |atol      mblen        strtod   wctomb   |
                |atof      mbstowcs     strtol   wcstombs |
                |atoi      mbtowc       stroul            |
                +-----------------------------------------+

2 The  contents are the same as the Standard C library, with the follow­
  ing modifications:

3 None of the headers shall define the type wchar_t (_lex.key_).

4 The function signature strchr(const char*, int) is replaced by the two
  declarations:

  const char* strchr(const char* s, int c);
        char* strchr(      char* s, int c);

5 both of which have the same behavior as the original declaration.

6 The  function  signature strpbrk(const char*, const char*) is replaced
  by the two declarations:

  const char* strpbrk(const char* s1, const char* s2);
        char* strpbrk(      char* s1, const char* s2);

7 both of which have the same behavior as the original declaration.

8 The function signature strrchr(const char*, int) is  replaced  by  the
  two declarations:

  const char* strrchr(const char* s, int c);
        char* strrchr(      char* s, int c);

9 both of which have the same behavior as the original declaration.

10The function signature strstr(const char*, const char*) is replaced by
  the two declarations:

  const char* strstr(const char* s1, const char* s2);
        char* strstr(      char* s1, const char* s2);

11both of which have the same behavior as the original declaration.

12The function signature memchr(const void*, int, size_type) is replaced
  by the two declarations:

  const void* memchr(const void* s, int c, size_type n);
        void* memchr(      void* s, int c, size_type n);

13both of which have the same behavior as the original declaration.  SEE
  ALSO: ISO C subclauses 7.3, 7.10.7, 7.10.8, and   7.11.   Amendment  1
  subclauses 4.4, 4.5, and 4.6.