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cposixlocalecrt

Is there a comprehensive list of functions affected by setlocale()?

So we all know that calling setlocale() will cause lots of C runtime functions to change their behaviour depending on the currently active locale. For example, when using a German locale, strtod() will suddenly expect a comma to separate the integer from the fractional part of a number because that's the way floating point numbers are notated in German.

What I'm looking for is a complete list of all C runtime functions that are potentially affected by a call to setlocale(). The man pages of setlocale mention some functions but the list is far from complete, e.g. strtod() isn't mentioned there at all.

Why am I looking for such a list? I need to transition several projects from the portable "C" locale to the system's locale and I don't want to break anything so I need to grep for all C runtime functions that are potentially affected by a locale change in order to adapt or fix the code to be compatible with an arbitrary locale instead of just the portable "C" locale.

Solution

  • I don't think this exists, but POSIX lists some functions that are directly dependant of locale and locale-relative variables The Open Group Base Specifications Issue 7, 2018 edition, 7 Locale. I don't think this is exhaustive (I'm retty sure it is not). It is said:

    The standard utilities in the Shell and Utilities volume of POSIX.1-2017 shall base their behavior on the current locale, as defined in the ENVIRONMENT VARIABLES section for each utility. The behavior of some of the C-language functions defined in the System Interfaces volume of POSIX.1-2017 shall also be modified based on a locale selection.

    Which means (to me): read the manual of the functions...

    You also have information about this in the standard C : 7.11.1 Locale control :

    7.11.1 Locale control

    7.11.1.1 The setlocale function

    The setlocale function selects the appropriate portion of the program’s locale as specified by the category and locale arguments. The setlocale function may be used to change or query the program’s entire current locale or portions thereof. The value LC_ALL for category names the program’s entire locale; the other values for category name only a portion of the program’s locale. LC_COLLATE affects the behavior of the strcoll and strxfrm functions. LC_CTYPE affects the behavior of the character handling functions, see 7.4) and the multibyte and wide character functions. LC_MONETARY affects the monetary formatting information returned by the localeconv function. LC_NUMERIC affects the decimal-point character for the formatted input/output functions and the string conversion functions, as well as the nonmonetary formatting information returned by the localeconv function. LC_TIME affects the behavior of the strftime and wcsftime functions.

    and

    7.4 Character handling

    7.4.1 Character classification functions

    7.4.1.1 The isalnum function

    7.4.1.2 The isalpha function

    7.4.1.3 The isblank function

    7.4.1.4 The iscntrl function

    7.4.1.5 The isdigit function

    7.4.1.6 The isgraph function

    7.4.1.7 The islower function

    7.4.1.8 The isprint function

    7.4.1.9 The ispunct function

    7.4.1.10 The isspace function

    7.4.1.11 The isupper function

    7.4.1.12 The isxdigit function

    7.4.2 Character case mapping functions

    7.4.2.1 The tolower function

    7.4.2.2 The toupper function