Doc No:   SC22/WG21/N2095
                                                  J16/06-0165
                                        Date:     2006-09-07
                                        Project:  JTC1.22.32
                                        Reply to: Robert Klarer
                                                  IBM Canada, Ltd.
                                                  klarer@ca.ibm.com

long long Goes to the Library

This paper proposes a small number of straightforward and probably uncontroversial changes to the Working Draft to complete integration of the long long and unsigned long long types with the C++ Standard Library.

This paper does not propose changes to the specification of the <random> library for the simple reason that to do so would likely cause confusion. Since the LWG has agreed in principle to N1932, "Random Number Generation in C++0X: A Comprehensive Proposal," I think that it's prudent to wait until that proposal is formally approved and reconciled with the Working Draft before we attempt to patch it.

Among the changes proposed below is the addition of new virtual member functions (overloads of do_get and do_put) to the num_get and num_put facets. Normally, the introduction of virtual functions to an existing class interface will pose backwards binary compatibility problems for implementers and, ultimately, programmers. I believe, however, that these virtual functions are already implemented widely as conforming extensions, so I predict that no backwards incompatibility will result from the changes.

Proposed Working Draft changes

18.2.1 Numeric limits

add the following to "Header synopsis":

        template<> class numeric_limits<long long>;
        template<> class numeric_limits<unsigned long long>;

20.5 Function objects

add the following to "Header <functional> synopsis":

        template <> struct hash<long long>;
        template <> struct hash<unsigned long long>;

21.4 Null-terminated sequence utilities:

add the following to "Table 63: Header <cstdlib> synopsis":

strtoull

22.2.2.1 Class template num_get

add the following public member functions to the class definition:

        iter_type get(iter_type in, iter_type end, ios_base&,
                      ios_base::iostate& err, long long& v)          const;
        iter_type get(iter_type in, iter_type end, ios_base&,
                      ios_base::iostate& err, unsigned long long& v) const;

add the following protected member functions to the class definition:

        virtual iter_type do_get(iter_type in, iter_type end, ios_base&,
                                 ios_base::iostate& err, long long& v)          const;
        virtual iter_type do_get(iter_type in, iter_type end, ios_base&,
                                 ios_base::iostate& err, unsigned long long& v) const;

22.2.2.1.1 num_get members

add the following:

        iter_type get(iter_type in, iter_type end, ios_base& str,
                      ios_base::iostate& err, long long& val)          const;
        iter_type get(iter_type in, iter_type end, ios_base& str,
                      ios_base::iostate& err, unsigned long long& val) const;

22.2.2.1.2 num_get virtual functions

to the list of function declarations before paragraph 1, add the following:

        iter_type do_get(iter_type in, iter_type end, ios_base& str,
                         ios_base::iostate& err, long long& val)          const;
        iter_type do_get(iter_type in, iter_type end, ios_base& str,
                         ios_base::iostate& err, unsigned long long& val) const;

To "Table 70: Length Modifier," add the following rows:

22.2.2.2 Class template num_put

add the following public member functions to the class definition:

        iter_type put(iter_type s, ios_base& f, char_type fill,
                      long long& v)          const;
        iter_type put(iter_type s, ios_base& f, char_type fill,
                      unsigned long long& v) const;

add the following protected member functions to the class definition:

        virtual iter_type do_put(iter_type, ios_base&, char_type fill,
                                 long long& v)          const;
        virtual iter_type do_put(iter_type, ios_base&, char_type fill,
                                 unsigned long long& v) const;

22.2.2.2.1 num_put members

to the list of function declarations before paragraph 1, add the following:

        iter_type put(iter_type out, ios_base& str, char_type fill,
                      long long& v)          const;
        iter_type put(iter_type out, ios_base& str, char_type fill,
                      unsigned long long& v) const;

22.2.2.2.1 num_put virtual functions

to the list of function declarations before paragraph 1, add the following:

        iter_type do_put(iter_type out, ios_base& str, char_type fill,
                         long long& v)          const;
        iter_type do_put(iter_type out, ios_base& str, char_type fill,
                         unsigned long long& v) const;

To "Table 73: Length Modifier," add the following rows:

These rows should appear above the row that reads "otherwise/none."

27.6.1.1 Class template basic_istream

Add the following formatted input operators to the class synopsis:

        // 27.6.1.2 Formatted input:
        ...
        basic_istream<charT, traits>& operator>>(long long& n);
        basic_istream<charT, traits>& operator>>(unsigned long long& n);

27.6.1.2.2 Arithmetic Extractors

Add the following formatted input operators above paragraph 1:

        operator>>(long long& val);
        operator>>(unsigned long long& val);

27.6.2.1 Class template basic_ostream

Add the following formatted input operators to the class synopsis:

        // 27.6.2.5 Formatted output:
        ...
        basic_ostream<charT, traits>& operator<<(long long n);
        basic_ostream<charT, traits>& operator<<(unsigned long long n);

27.6.2.5 Arithmetic Inserters

Add the following formatted output operators above paragraph 1:

        operator<<(long long val);
        operator<<(unsigned long long val);

end of paper.