STRXFRM(3C)STRXFRM(3C)NAMEstrxfrm - string transformation
size_t strxfrm(char *restrict s1, const char *restrict s2, size_t n);
The strxfrm() function transforms the string pointed to by s2 and
places the resulting string into the array pointed to by s1. The trans‐
formation is such that if strcmp(3C) is applied to two transformed
strings, it returns a value greater than, equal to or less than 0, cor‐
responding to the result of strcoll(3C) applied to the same two origi‐
nal strings. No more than n bytes are placed into the resulting array
pointed to by s1, including the terminating null byte. If n is 0, s1
is permitted to be a null pointer. If copying takes place between
objects that overlap, the behavior is undefined.
The strxfrm() function does not change the setting of errno if success‐
Since no return value is reserved to indicate an error, an application
wishing to check for error situations should set errno to 0, then call
strxfrm(), then check errno.
Upon successful completion, strxfrm() returns the length of the trans‐
formed string (not including the terminating null byte). If the value
returned is n or more, the contents of the array pointed to by s1 are
On error, strxfrm() may set errno but no return value is reserved to
indicate the error.
The transformation function is such that two transformed strings can be
ordered by strcmp(3C) as appropriate to collating sequence information
in the program's locale (category LC_COLLATE).
The fact that when n is 0, s1 is permitted to be a null pointer, is
useful to determine the size of the s1 array prior to making the trans‐
Example 1 A sample of using the strxfm() function.
The value of the following expression is the size of the array needed
to hold the transformation of the string pointed to by s.
1 + strxfrm(NULL, s, 0);
LC_COLLATE database for locale
See attributes(5) for descriptions of the following attributes:
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
│CSI │ Enabled │
│Interface Stability │ Standard │
│MT-Level │ MT-Safe with exceptions │
The strxfrm() function can be used safely in a multithreaded applica‐
tion, as long as setlocale(3C) is not being called to change the
SEE ALSOlocaledef(1), setlocale(3C), strcmp(3C), strcoll(3C), wscoll(3C),
attributes(5), environ(5), standards(5)
Dec 10, 2003 STRXFRM(3C)