memcmp() In C

Purpose Of memcmp()

memcmp() is one of the inbuilt string function in C programming which is used to compare the first n bytes of memory location str1 and memory location str2.

How memcmp() Works

The following diagram clearly illustrate the working principle of memcmp() inbuilt string function in C.

In the above diagram memcmp() takes three parameters, first two parameters str1 and str2 are in string type whereas third parameter n is of integer type. Here integer n tells the compiler, how much memory bytes of two parameters str1 and str2 is to be compared.

memcmp() Return Value

Syntax Of memcmp()

• memcmp() accepts three parameters
• First two parameters str1 and str2 are in string type whereas third parameter n is of integer type.
• To use memcmp() inbuilt string function in C, we need to declare #include<string.h> header file.

memcmp(str1, str2, n);

C Program - memcmp()

Let us work through memcmp() function, In the following program we will compare the first n bytes of memory location str1 and memory location str2 using memcmp() in-built string function.

#include <stdio.h>
#include<string.h>
int main()
{
char str1[15] = "ABD";
char str2[15] = "abd";
int res;
res = memcmp(str1, str2, 1);
if(res > 0)
  printf("str2 is less than str1");
else if(res < 0)
  printf("str1 is less than str2");
else
  printf("str1 is equal to str2");
return 0;
}

str1 is less than str2

C Program - Without memcmp()

Let us compare the first n bytes of memory location str1 and memory location str2 without using memcmp inbuilt string function.

#include <stdio.h>
#include<string.h>
int main()
{
char str1[15]="acc";
char str2[15]="avd";
char len = 3;
int i, j = 0;
for(i =0; i<len; i++)
{
if(str1[i] == str2[i]){
if(64

str1 is lesser than str2.

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