The Open Group Base Specifications Issue 7
IEEE Std 1003.1-2008, 2016 Edition
Copyright © 2001-2016 The IEEE and The Open Group

#### NAME

> strcasecmp, strcasecmp_l, strncasecmp, strncasecmp_l - case-insensitive string comparisons

#### SYNOPSIS

> ``#include <strings.h>
> int strcasecmp(const char *`s1`, const char *`s2`);
> int strcasecmp_l(const char *`s1`, const char *`s2`,
> locale_t` locale`);
> int strncasecmp(const char *`s1`, const char *`s2`, size_t` n`);
> int strncasecmp_l(const char *`s1`, const char *`s2`,
> size_t` n`, locale_t` locale`);
> ``

#### DESCRIPTION

> The strcasecmp() and strcasecmp_l() functions shall compare, while ignoring differences in case, the string pointed to by s1 to the string pointed to by s2. The strncasecmp() and strncasecmp_l() functions shall compare, while ignoring differences in case, not more than n bytes from the string pointed to by s1 to the string pointed to by s2.

> The strcasecmp() and strncasecmp() functions use the current locale to determine the case of the characters.

> The strcasecmp_l() and strncasecmp_l() functions use the locale represented by locale to determine the case of the characters.

> When the LC_CTYPE category of the locale being used is from the POSIX locale, these functions shall behave as if the strings had been converted to lowercase and then a byte comparison performed. Otherwise, the results are unspecified.

> The behavior is undefined if the locale argument to strcasecmp_l() or strncasecmp_l() is the special locale object LC_GLOBAL_LOCALE or is not a valid locale object handle.

#### RETURN VALUE

> Upon completion, strcasecmp() and strcasecmp_l() shall return an integer greater than, equal to, or less than 0, if the string pointed to by s1 is, ignoring case, greater than, equal to, or less than the string pointed to by s2, respectively.

> Upon successful completion, strncasecmp() and strncasecmp_l() shall return an integer greater than, equal to, or less than 0, if the possibly null-terminated array pointed to by s1 is, ignoring case, greater than, equal to, or less than the possibly null-terminated array pointed to by s2, respectively.

#### ERRORS

> No errors are defined.

The following sections are informative.

#### EXAMPLES

> None.

#### APPLICATION USAGE

> None.

#### RATIONALE

> None.

#### FUTURE DIRECTIONS

> None.

#### SEE ALSO

> wcscasecmp

> XBD <strings.h>

#### CHANGE HISTORY

> First released in Issue 4, Version 2.

#### Issue 5

> Moved from X/OPEN UNIX extension to BASE.

#### Issue 7

> The strcasecmp() and strncasecmp() functions are moved from the XSI option to the Base.

> The strcasecmp_l() and strncasecmp_l() functions are added from The Open Group Technical Standard, 2006, Extended API Set Part 4.

> POSIX.1-2008, Technical Corrigendum 1, XSH/TC1-2008/0589 [302], XSH/TC1-2008/0590 [294], XSH/TC1-2008/0591 [283], and XSH/TC1-2008/0592 [283] are applied.

End of informative text.

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