strcasecmp, strncasecmp - compare two strings ignoring case

       For an explanation of the terms used in this section, see attributes(7).
       ┌──────────────────────────────────────────────────────────────────────┬───────────────┬────────────────┐
       │ Interface                                                            │ Attribute     │ Value          │
       ├──────────────────────────────────────────────────────────────────────┼───────────────┼────────────────┤
       │ strcasecmp(), strncasecmp()                                          │ Thread safety │ MT-Safe locale │
       └──────────────────────────────────────────────────────────────────────┴───────────────┴────────────────┘

       The  strcasecmp() function performs a byte-by-byte comparison of the strings s1 and s2, ignoring the case
       of the characters.  It returns an integer less than, equal to, or greater  than  zero  if  s1  is  found,
       respectively, to be less than, to match, or be greater than s2.

       The strncasecmp() function is similar, except that it compares no more than n bytes of s1 and s2.

       4.4BSD, POSIX.1-2001.

       The strcasecmp() and strncasecmp() functions first appeared  in  4.4BSD,  where  they  were  declared  in
       <string.h>.   Thus,  for  reasons  of  historical  compatibility,  the  glibc <string.h> header file also
       declares these functions, if the _DEFAULT_SOURCE (or, in glibc 2.19  and  earlier,  _BSD_SOURCE)  feature
       test macro is defined.

       The POSIX.1-2008 standard says of these functions:

              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.

       Standard C library (libc, -lc)

       strcasecmp, strncasecmp - compare two strings ignoring case

       The  strcasecmp() and strncasecmp() functions return an integer less than, equal to, or greater than zero
       if s1 is, after ignoring case, found to be less than, to match, or be greater than s2, respectively.

memcmp(3), strcmp(3), strcoll(3), string(3), strncmp(3), wcscasecmp(3), wcsncasecmp(3)

Linux man-pages 6.9.1                              2024-05-02                                      strcasecmp(3)

       POSIX.1-2008.

#include<strings.h>intstrcasecmp(constchar*s1,constchar*s2);intstrncasecmp(constchars1[.n],constchars2[.n],size_tn);