strxfrm(3)strxfrm(3)NAMEstrxfrm - Transforms string for collation in current locale
SYNOPSIS
#include <string.h>
size_t strxfrm(
char *s1,
const char *s2,
size_t n );
LIBRARY
Standard C Library (libc)
STANDARDS
Interfaces documented on this reference page conform to industry stan‐
dards as follows:
strxfrm(): XPG4, XPG4-UNIX
Refer to the standards(5) reference page for more information about
industry standards and associated tags.
PARAMETERS
Specifies the destination string. Specifies the string to be trans‐
formed. Specifies the maximum number of bytes to store in the trans‐
formed string.
DESCRIPTION
The strxfrm() function transforms the string pointed to by the s2
parameter into an internal form suitable for collation and places the
result in the address specified by s1. This transformation is performed
as appropriate to the LC_COLLATE category of the current locale. When
the strcmp() function is applied to two transformed strings, a value
greater than, equal to, or less than 0 (zero) is returned. The returned
value corresponds to the same value that is returned when the strcoll()
function is applied to the same two original transformed strings. The
transformed string can be longer than the original string. No more than
n characters are placed in the location pointed to by the s1 parameter,
including the terminating null character. When n is 0 (zero), the s1
parameter can be a null pointer. When operating on overlapping strings,
the behavior of this function is unreliable.
NOTES
If you are doing multiple comparisons using the same set of text
strings, the strxfrm() transformation function in conjunction with the
strcmp() function may be more efficient than using the strcoll() colla‐
tion function because the string is transformed based on the locale
tables only once. However, the transformation function must convert all
characters in the string for each level of a multi-level collation. In
comparison, the collation function stops comparing characters at the
first inequality. These efficiency tradeoffs make the most efficient
method for a specific application dependent on both the number of
repeated comparisons for each string and the contents of each string.
RETURN VALUES
Upon successful completion, the strxfrm() function returns the number
of bytes required to store the transformed string (not including the
terminating null byte). If this is greater than or equal to the value
of the n parameter, which specifies the maximum number of bytes that
can be stored in s1, the contents of s1 are indeterminate.
ERRORS
If the following condition occurs, the strxfrm() function sets errno to
the corresponding value. The s2 parameter contains codes outside the
domain of the collating sequence defined by the current locale.
SEE ALSO
Functions: setlocale(3), strcoll(3), string(3), strcmp(3), wcsxfrm(3)
Standards: standards(5)strxfrm(3)
