Issue 0503: Hexadecimal floating-point and strtod

This issue has been automatically converted from the original issue lists and some formatting may not have been preserved.

Authors: WG14, Clark Nelson
Date: 2016-09-13
Reference document: N2082
Submitted against: C11 / C17
Status: Closed
Converted from: n2396.htm

Summary

C11 7.22.1.3 paragraph 3 bullet 2 says:

a 0x or 0X, then a nonempty sequence of hexadecimal digits optionally containing a decimal-point character, then an optional binary exponent part as defined in 6.4.4.2;

but the grammar in C11 6.4.4.2 makes the binary-exponent-part mandatory, not optional.

Suggested resolution

Strike "optional" before "binary exponent part" and add a comma before "as defined in" to highlight that "as defined in" applies to the entire sentence, not only to the last part.

Comment from WG14 on 2017-11-03:

Oct 2016 meeting

Committee Discussion

This turns out to not be a defect.

Proposed Committee Response

The reference to §6.4.4.2 is only for the definition of "binary exponent part", it does not apply to the entire sentence. The specification of allowable subject sequences for these library functions is intentionally looser than the grammar for floating constants in order to accept as many reasonable input strings as possible. Thus, both 123 and 0x123 are valid subject sequences even though neither is acceptable as a floating constant.