strxfrm - string transformation
size_t strxfrm(char *s1, const char *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 transformation is such that if strcmp(3C) is
applied to two transformed strings, it returns a value
greater than, equal to or less than 0, corresponding to the
result of strcoll(3C) applied to the same two original
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
Upon successful completion, strxfrm() returns the length of
the transformed 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 indeterminate.
On failure, strxfrm() returns (size_t)-1.
The transformation function is such that two transformed
strings can be ordered by strcmp(3C) as appropriate to col-
lating sequence information in the program's locale
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 transformation.
Because no return value is reserved to indicate an error, an
application wishing to check for error situations should set
errno to 0, then call strcoll(3C), then check errno and if
it is non-zero, assume an error has occurred.
This issue is aligned with the ANSI C standard; this does
not affect compatibility with XPG3 applications. Reliable
error detection by this function was never guaranteed.
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 attri-
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| MT-Level | MT-Safe with exceptions |
| CSI | Enabled |
localedef(1), setlocale(3C), strcmp(3C), strcoll(3C),
wscoll(3C), attributes(5), environ(5), standards(5)
The strxfrm() function can be used safely in a multithreaded
application, as long as setlocale(3C) is not being called to
change the locale.
Man(1) output converted with