memcmp

Function Usage

Compares the contents of two memory blocks byte by byte. If the contents of the two memory blocks are different, the difference is returned. Otherwise, 0 is returned.

Function Syntax

int memcmp(const void *ptr1, const void *ptr2, size_t num);

Parameters

Return Value

• Success:
  • If the contents of the two memory blocks are the same, 0 is returned.
  • If ptr1 is less than ptr2, -1 is returned.
  • If ptr1 is greater than ptr2, 1 is returned.
• Failure: See those of open source glibc. No other exception values will be returned.

The comparison is performed byte by byte until a difference is found or all the num bytes are compared.

Example

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

int main() {
    char str1[] = "Hello, World!";
    char str2[] = "Hello, World!";
    char str3[] = "Hello, World";

    int result1 = memcmp(str1, str2, sizeof(str1));
    if (result1 == 0) {
        printf("str1 and str2 are equal\n");
    } else {
        printf("str1 and str2 are not equal\n");
    }

    int result2 = memcmp(str1, str3, sizeof(str1));
    if (result2 != 0) {
        printf("str1 and str3 are not equal\n");
    } else {
        printf("str1 and str3 are equal\n");
    }
    return 0;
}

Output:

str1 and str2 are equal
str1 and str3 are not equal