The Single UNIX ® Specification, Version 2
Copyright © 1997 The Open Group


strxfrm - string transformation


#include <string.h>

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() is applied to two transformed strings, it returns a value greater than, equal to or less than 0, corresponding to the result of strcoll() 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 behaviour is undefined.

The strxfrm() function will not change the setting of errno if successful.

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(), then check errno.


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 error, strxfrm() may set errno but no return value is reserved to indicate an error.


The strxfrm() function may fail if:
The string pointed to by the s2 argument contains characters outside the domain of the collating sequence.




The transformation function is such that two transformed strings can be ordered by strcmp() 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 transformation.




strcmp(), strcoll(), <string.h>.


Derived from the ISO C standard.

UNIX ® is a registered Trademark of The Open Group.
Copyright © 1997 The Open Group
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