strxfrm, wcsxfrm, _strxfrm_l, _wcsxfrm_l

Transform a string based on locale-specific information.

Syntax

size_t strxfrm(
   char *strDest,
   const char *strSource,
   size_t count
);
size_t wcsxfrm(
   wchar_t *strDest,
   const wchar_t *strSource,
   size_t count
);
size_t _strxfrm_l(
   char *strDest,
   const char *strSource,
   size_t count,
   _locale_t locale
);
size_t wcsxfrm_l(
   wchar_t *strDest,
   const wchar_t *strSource,
   size_t count,
   _locale_t locale
);

Parameters

strDest
Destination string.

strSource
Source string.

count
Maximum number of characters to place in strDest.

locale
The locale to use.

Return value

Returns the length of the transformed string, not counting the terminating null character. If the return value is greater than or equal to count, the content of strDest is unpredictable. On an error, each function sets errno and returns INT_MAX. For an invalid character, errno is set to EILSEQ.

Remarks

The strxfrm function transforms the string pointed to by strSource into a new collated form that is stored in strDest. No more than count characters, including the null character, are transformed and placed into the resulting string. The transformation is made using the locale's LC_COLLATE category setting. For more information on LC_COLLATE, see setlocale. strxfrm uses the current locale for its locale-dependent behavior; _strxfrm_l is identical except that it uses the locale passed in instead of the current locale. For more information, see Locale.

After the transformation, a call to strcmp with the two transformed strings yields results identical to the results of a call to strcoll applied to the original two strings. As with strcoll and stricoll, strxfrm automatically handles multibyte-character strings as appropriate.

wcsxfrm is a wide-character version of strxfrm; the string arguments of wcsxfrm are wide-character pointers. For wcsxfrm, after the string transformation, a call to wcscmp with the two transformed strings yields results identical to the results of a call to wcscoll applied to the original two strings. wcsxfrm and strxfrm behave identically otherwise. wcsxfrm uses the current locale for its locale-dependent behavior; _wcsxfrm_l uses the locale passed in instead of the current locale.

These functions validate their parameters. If strSource is a null pointer, or strDest is a NULL pointer (unless count is zero), or if count is greater than INT_MAX, the invalid parameter handler is invoked, as described in Parameter validation . If execution is allowed to continue, these functions set errno to EINVAL and return INT_MAX.

By default, this function's global state is scoped to the application. To change this behavior, see Global state in the CRT.

Generic-text routine mappings

TCHAR.H routine	_UNICODE and _MBCS not defined	_MBCS defined	_UNICODE defined
_tcsxfrm	strxfrm	strxfrm	wcsxfrm
_tcsxfrm_l	_strxfrm_l	_strxfrm_l	_wcsxfrm_l

In the "C" locale, the order of the characters in the character set (ASCII character set) is the same as the lexicographic order of the characters. However, in other locales, the order of characters in the character set may differ from the lexicographic character order. For example, in certain European locales, the character 'a' (value 0x61) precedes the character 'ä' (value 0xE4) in the character set, but the character 'ä' precedes the character 'a' lexicographically.

In locales for which the character set and the lexicographic character order differ, use strxfrm on the original strings and then strcmp on the resulting strings to produce a lexicographic string comparison according to the current locale's LC_COLLATE category setting. Thus, to compare two strings lexicographically in the above locale, use strxfrm on the original strings, then strcmp on the resulting strings. Alternately, you can use strcoll rather than strcmp on the original strings.

strxfrm is basically a wrapper around LCMapString with LCMAP_SORTKEY.

The value of the following expression is the size of the array needed to hold the strxfrm transformation of the source string:

1 + strxfrm( NULL, string, 0 )

In the "C" locale only, strxfrm is equivalent to the following function calls:

strncpy( _string1, _string2, _count );
return( strlen( _string1 ) );

Requirements

Routine	Required header
strxfrm	<string.h>
wcsxfrm	<string.h> or <wchar.h>
_strxfrm_l	<string.h>
_wcsxfrm_l	<string.h> or <wchar.h>

For more compatibility information, see Compatibility.

See also

Data conversion
localeconv
setlocale, _wsetlocale
Locale
String manipulation
strcoll functions
strcmp, wcscmp, _mbscmp
strncmp, wcsncmp, _mbsncmp, _mbsncmp_l