C memcmp() function

C memcmp() function - compare bytes in memory

Syntax:

int memcmp(const void *str1, const void *str2, size_t n)

The memcmp() function compares the first n bytes of str1 and str2.

Parameters:

Return value from memcmp()

• if Return value < 0 then it indicates str1 is less than str2.
• if Return value > 0 then it indicates str2 is less than str1.
• if Return value = 0 then it indicates str1 is equal to str2.

Example: memcmp() function

The following program uses memcmp to compare two strings.

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

int main( void )
{
   char str1[] = "12345678901400345678";
   char str2[] = "12345678901297650033";
   int result;
   printf("Original text:");
   printf("\n%s",str1);
   printf("\n%s",str2);
   printf( "\n\nCompare first 10 characters of the said two strings");
   result = memcmp( str1, str2, 10 );
   if( result < 0 )
      printf( "\nFirst is less than second.\n" );
   else if( result == 0 )
      printf( "\nFirst is equal to second.\n" );
   else
      printf( "\nFirst is greater than second.\n" );

   printf( "\n\nCompare first 12 characters of the said two strings");
   result = memcmp( str1, str2, 12 );
   if( result < 0 )
      printf( "\nFirst is less than second.\n");
   else if( result == 0 )
      printf( "\nFirst is equal to second.\n");
   else
      printf( "\nFirst is greater than second.\n");   
      
   char str3[] = "12345678901100345678";
   char str4[] = "12345678901297650033";   
   printf("\n\nOriginal text:");
   printf("\n%s",str3);
   printf("\n%s",str4);
   printf( "\n\nCompare first 19 characters of the said two strings");
   result = memcmp( str3, str4, 19 );
   if( result < 0 )
      printf( "\nFirst is less than second.\n");
   else if( result == 0 )
      printf( "\nFirst is equal to second.\n");
   else
      printf( "\nFirst is greater than second.\n");         
}

Output:

Original text:
12345678901400345678
12345678901297650033

Compare first 10 characters of the said two strings
First is equal to second.


Compare first 12 characters of the said two strings
First is greater than second.


Original text:
12345678901100345678
12345678901297650033

Compare first 19 characters of the said two strings
First is less than second.

C Programming Code Editor:

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