Interpretations

Answering questions that may arise related to the meaning of portions of an IEEE standard concerning specific applications.

IEEE Standards Interpretations for IEEE Std 1003.1™-2001 IEEE Standard for Information Technology - Portable Operating System Interface (POSIX®)

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Interpretation Request #15
Topic: Defect in XSH strtold/wcstold () Relevant Sections: exponent parts

XSH6's description of the strtod(), strtof(), and strtold() functions on P1441 and of the wcstod(), wcstof(), and wcstold() functions on P1611 are taken directly from the C standard subclauses 7.20.1.3 and 7.24.4.1.1, respectively. When these descriptions were incorporated into XSH6, however, the explanation that the terms "optional exponent part" and "optional binary exponent part" were defined in C standard subclause 6.4.4.2 was dropped. (Since interstandard subclause references should be avoided, dropping the subclause reference was correct.) Unfortunately, however, IEEE Std 1003.1-2001 does not define these terms at all in this context. The strings to be recognized by these functions are similar to, but not identical to the 1999 C standard's definitions of floating constants. (Exceptions are noted on P1441-1442, L44631-44644 and P1611-1612, L49629-49642.) Note that the references to "If the subject sequence has the expected form for a floating-point number" on P1441, L44631 and on P1611, L49629 are not referring to subclause 6.4.4.2 in the 1999 C Standard; they are referring to the forms described on P1441, L44615-44630 and on P1611, L49612-49628. For the XSH specification of these functions to be complete, the terms "exponent part" and "binary exponent part" need to be defined.

Change: character, then an optional exponent part on P1441, L44617-44618 to: character; then an optional exponent part consisting of the character 'e' or the character 'E', optionally followed by a '+' or '-' character, and then followed by one or more decimal digits Change P1441, L44620 from: character, then an optional binary exponent part to: character; then an optional binary exponent part consisting of the character 'p' or the character 'P', optionally followed by a '+' or '-' character, and then followed by one or more decimal digits Change: character, then an optional exponent part on P1611, L49614-49615 to: character; then an optional exponent part consisting of the wide character L'e' or the wide character L'E', optionally followed by a L'+' or L'-' wide character, and then one or more decimal digits Change P1611, L49617 from: character, then an optional binary exponent part to: character; then an optional binary exponent part consisting of the wide character L'p' or the wide character L'P', optionally followed by a L'+' or L'-' wide character, and then followed by one or more decimal digits

Interpretation Response
The standard states that the current requirements and conforming implementations must conform to this. However, concerns have been raised about this which are being referred to the sponsor.

Rationale for Interpretation
None.