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memcmp, wmemcmp

Compares characters in two buffers.


int memcmp(
   const void *buffer1,
   const void *buffer2,
   size_t count
int wmemcmp(
   const wchar_t * buffer1,
   const wchar_t * buffer2,
   size_t count


First buffer.

Second buffer.

Number of characters to compare. (Compares bytes for memcmp, wide characters for wmemcmp).

Return value

The return value indicates the relationship between the buffers.

Return value Relationship of first count characters of buf1 and buf2
< 0 buffer1 less than buffer2
0 buffer1 identical to buffer2
> 0 buffer1 greater than buffer2


Compares the first count characters of buffer1 and buffer2 and returns a value that indicates their relationship. The sign of a non-zero return value is the sign of the difference between the first differing pair of values in the buffers. The values are interpreted as unsigned char for memcmp, and as wchar_t for wmemcmp.


Routine Required header
memcmp <memory.h> or <string.h>
wmemcmp <wchar.h>

For more compatibility information, see Compatibility.


All versions of the C run-time library.


// crt_memcmp.c
/* This program uses memcmp to compare
* the strings named first and second. If the first
* 19 bytes of the strings are equal, the program
* considers the strings to be equal.

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

int main( void )
   char first[]  = "12345678901234567890";
   char second[] = "12345678901234567891";
   int int_arr1[] = {1,2,3,4};
   int int_arr2[] = {1,2,3,4};
   int result;

   printf( "Compare '%.19s' to '%.19s':\n", first, second );
   result = memcmp( first, second, 19 );
   if( result < 0 )
      printf( "First is less than second.\n" );
   else if( result == 0 )
      printf( "First is equal to second.\n" );
      printf( "First is greater than second.\n" );

   printf( "Compare '%d,%d' to '%d,%d':\n", int_arr1[0], int_arr1[1], int_arr2[0], int_arr2[1]);
   result = memcmp( int_arr1, int_arr2, sizeof(int) * 2 );
   if( result < 0 )
      printf( "int_arr1 is less than int_arr2.\n" );
   else if( result == 0 )
      printf( "int_arr1 is equal to int_arr2.\n" );
      printf( "int_arr1 is greater than int_arr2.\n" );
Compare '1234567890123456789' to '1234567890123456789':
First is equal to second.
Compare '1,2' to '1,2':
int_arr1 is equal to int_arr2.

See also

Buffer manipulation
memchr, wmemchr
memcpy, wmemcpy
memset, wmemset
strcmp, wcscmp, _mbscmp
strncmp, wcsncmp, _mbsncmp, _mbsncmp_l