strcmp(3)                  Library Functions Manual                  strcmp(3)

NAME
       strcmp - strings compare

LIBRARY
       Standard C library (libc, -lc)

SYNOPSIS
       #include <string.h>

       int strcmp(const char *s1, const char *s2);

DESCRIPTION
       The strcmp() function compares the two strings s1 and s2, as if by
       calling memcmp(3).

       It is equivalent to

           memcmp(s1, s2, MIN(strlen(s1),strlen(s2))+1)

RETURN VALUE
       See memcmp(3).

ATTRIBUTES
       For an explanation of the terms used in this section, see
       attributes(7).

       +--------------------------------------------+---------------+---------+
       |Interface                                   | Attribute     | Value   |
       +--------------------------------------------+---------------+---------+
       |strcmp ()                                   | Thread safety | MT-Safe |
       +--------------------------------------------+---------------+---------+
STANDARDS
       C11, POSIX.1-2008.

HISTORY
       POSIX.1-2001, C89, SVr4, 4.3BSD.

CAVEATS
       The locale is not taken into account (for a locale-aware comparison,
       see strcoll(3)).

EXAMPLES
       The program below can be used to demonstrate the operation of strcmp().

           $ ./strcmp ABC ABC;
           <str1> and <str2> are equal
           $ ./strcmp ABC AB;      # 'C' is ASCII 67; 'C' - '\0' = 67
           <str1> is greater than <str2> (67)
           $ ./strcmp ABA ABZ;     # 'A' is ASCII 65; 'Z' is ASCII 90
           <str1> is less than <str2> (-25)
           $ ./strcmp ABJ ABC;
           <str1> is greater than <str2> (7)
           $ ./strcmp $'\201' A;   # 0201 - 0101 = 0100 (or 64 decimal)
           <str1> is greater than <str2> (64)

       The last example uses bash(1)-specific syntax to produce a string
       containing an 8-bit ASCII code; the result demonstrates that the string
       comparison uses unsigned characters.

   Program source
       // strcmp.c
       // Licensed under GNU General Public License v2 or later.

       #include <stdio.h>
       #include <stdlib.h>
       #include <string.h>

       int
       main(int argc, char *argv[])
       {
           int res;

           if (argc != 3) {
               fprintf(stderr, "Usage: %s <str1> <str2>\n", argv[0]);
               exit(EXIT_FAILURE);
           }

           res = strcmp(argv[1], argv[2]);

           if (res == 0) {
               printf("<str1> and <str2> are equal");
               printf("\n");
           } else if (res < 0) {
               printf("<str1> is less than <str2> (%d)\n", res);
           } else {
               printf("<str1> is greater than <str2> (%d)\n", res);
           }

           exit(EXIT_SUCCESS);
       }

SEE ALSO
       memcmp(3), strcasecmp(3), strcoll(3), streq(3), string(3),
       strverscmp(3), wcscmp(3)

Linux man-pages 6.19              2026-08-10                         strcmp(3)