scanf family and the strtod family?This issue has been automatically converted from the original issue lists and some formatting may not have been preserved.
Authors: Fred Tydeman, Project Editor (P.J. Plauger)
Date: 1993-06-07
Submitted against: C90
Status: Closed
Converted from: dr.htm, dr_058.html
What is the minimum value for the maximum number of digits in a number that can
be processed by the scanf family and the strtod family?
Parts of the the C Standard that may help answer the question follow. Subclause
7.9.6.1The fprintf function, page 134, lines 16-18:
Environmental limit. The minimum value for the maximum number of characters produced by any single conversion shall be 509.
But, note, there is no such environmental limit for fscanf.
Subclause 5.2.4.1 Translation limits, page 13, line 17:
- 509 characters in a logical source line
But, note, there is no execution limit. Subclause 5.2.4.1 Translation Limits, page 13, line 19:
- 32767 bytes in an object (in a hosted environment only)
Consider the number 1.0 written as .00000...00001e32759 that is 32767
characters long (including terminator). There is only one significant digit, the
1. It can be stored in an array of 32767 characters, so it should be possible
to pass this string to atof, strtod, or sscanf and get the value 1.0.
Correct?
Comment from WG14 on 1997-09-23:
You are correct; the C Standard imposes no execution limit on the maximum number
of digits in the subject sequence of fscanf conversion specifiers and the
strto* functions, other than on the size of objects.