strxfrm
Defined in header <string.h>
|
||
(until C99) | ||
(since C99) | ||
Transforms the null-terminated byte string pointed to by src
into the implementation-defined form such that comparing two transformed strings with strcmp gives the same result as comparing the original strings with strcoll, in the current C locale.
The first count
characters of the transformed string are written to destination, including the terminating null character, and the length of the full transformed string is returned, excluding the terminating null character.
The behavior is undefined if the dest
array is not large enough. The behavior is undefined if dest
and src
overlap.
If count
is 0, then dest
is allowed to be a null pointer.
Notes
The correct length of the buffer that can receive the entire transformed string is 1+strxfrm(NULL, src, 0)
This function is used when making multiple locale-dependent comparisons using the same string or set of strings, because it is more efficient to use strxfrm
to transform all the strings just once, and subsequently compare the transformed strings with strcmp.
Parameters
dest | - | pointer to the first element of the array where the transformed string will be written |
src | - | pointer to the first character of a null-terminated byte string to transform |
count | - | maximum number of characters to be written |
Return value
The length of the transformed string, not including the terminating null-character.
Example
#include <stdio.h> #include <string.h> #include <locale.h> int main(void) { setlocale(LC_COLLATE, "cs_CZ.iso88592"); const char *in1 = "hrnec"; char out1[1+strxfrm(NULL, in1, 0)]; strxfrm(out1, in1, sizeof out1); const char *in2 = "chrt"; char out2[1+strxfrm(NULL, in2, 0)]; strxfrm(out2, in2, sizeof out2); printf("In the Czech locale: "); if(strcmp(out1, out2) < 0) printf("%s before %s\n",in1, in2); else printf("%s before %s\n",in2, in1); printf("In lexicographical comparison: "); if(strcmp(in1, in2)<0) printf("%s before %s\n",in1, in2); else printf("%s before %s\n",in2, in1); }
Output:
In the Czech locale: hrnec before chrt In lexicographical comparison: chrt before hrnec
References
- C11 standard (ISO/IEC 9899:2011):
- 7.24.4.5 The strxfrm function (p: 366-367)
- C99 standard (ISO/IEC 9899:1999):
- 7.21.4.5 The strxfrm function (p: 329-330)
- C89/C90 standard (ISO/IEC 9899:1990):
- 4.11.4.5 The strxfrm function
See also
compares two strings in accordance to the current locale (function) | |
(C95) |
compares two wide strings in accordance to the current locale (function) |
compares two strings (function) | |
(C95) |
transform a wide string so that wcscmp would produce the same result as wcscoll (function) |