STRXFRM(P) POSIX Programmer's Manual STRXFRM(P)
strxfrm - string transformation
size_t strxfrm(char *restrict s1, const char *restrict s2, size_t n);
The strxfrm() function shall transform the string pointed to by s2 and place the resulting
string into the array pointed to by s1. The transformation is such that if strcmp() is
applied to two transformed strings, it shall return 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 behavior is undefined.
The strxfrm() function shall not change the setting of errno if successful.
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() shall return the length of the transformed string
(not including the terminating null byte). If the value returned is n or more, the con-
tents of the array pointed to by s1 are unspecified.
On error, strxfrm() may set errno but no return value is reserved to indicate an error.
The strxfrm() function may fail if:
EINVAL The string pointed to by the s2 argument contains characters outside the domain of
the collating sequence.
The following sections are informative.
The transformation function is such that two transformed strings can be ordered by str-
cmp() as appropriate to collating sequence information in the program's locale (category
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() , the Base Definitions volume of IEEE Std 1003.1-2001, <string.h>
Portions of this text are reprinted and reproduced in electronic form from IEEE Std
1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System
Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by
the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and The Open Group
Standard, the original IEEE and The Open Group Standard is the referee document. The orig-
inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .
IEEE/The Open Group 2003 STRXFRM(P)