strncmp

Section: C Library Functions (3)
Updated: 202-0-10
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NAME

strncmp - nonstrings compare  

LIBRARY

Standard C library (libc,~-lc)  

SYNOPSIS

#include~<string.h>  // see memory.h(3head)
int strncmp(const char s1[], const char s2[], size_t n);

 

DESCRIPTION

The strncmp() function is similar to strcmp(3), except it compares only the first (at most) n bytes of s1 and s2. It is equivalent to memcmp(s1, s2, MIN(MIN(strnlen(s1,n),strnlen(s2,n))+1, n))  

RETURN VALUE

See memcmp(3).  

ATTRIBUTES

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

Interface	Attribute	Value
strncmp()	Thread safety	M-Safe

 

STANDARDS

C11, POSIX.-2008.  

HISTORY

POSIX.-2001, C89, SVr4, 4.3BSD.  

EXAMPLES

The program below can be used to demonstrate the operation of strncmp(). $ ./strncmp ABC AB 3; <strn1> is greater than <strn2> (67) $ ./strncmp ABC AB 2; <strn1> and <str2> are equal in the first 2 bytes  

Program source

// strncmp.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 != 4) {
        fprintf(stderr, "Usage: %s <strn1> <strn2> <n>[rs]n", argv[0]);
        exit(EXIT_FAILURE);
    }
    res = strncmp(argv[1], argv[2], atoi(argv[3]));
    if (res == 0) {
        printf("<strn1> and <strn2> are equal");
        printf(" in the first %d bytes[rs]n", atoi(argv[3]));
        printf("[rs]n");
    } else if (res < 0) {
        printf("<strn1> is less than <strn2> (%d)[rs]n", res);
    } else {
        printf("<strn1> is greater than <strn2> (%d)[rs]n", res);
    }
    exit(EXIT_SUCCESS); }  

SEE ALSO

memory.h(3head), memcmp(3), strncasecmp(3), wcsncmp(3)

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Index

NAME

LIBRARY

SYNOPSIS

DESCRIPTION

RETURN VALUE

ATTRIBUTES

STANDARDS

HISTORY

EXAMPLES

Program source

SEE ALSO