memcmp() function in C

 The memcmp() function in C, available in the header, is used to compare two memory blocks.

 It compares the first n bytes of the memory block pointed to by ptr1 with the first n bytes of the memory block pointed to by ptr2.

Syntax of memcmp() function in C:

#include<string.h>
int memcmp(const void *ptr1, const void *ptr2, size_t n);

 ptr1: Pointer to the first memory block.

 ptr2: Pointer to the second memory block.

 n: Number of bytes to compare.

Return Value:

 Returns an integer less than, equal to, or greater than zero if the first n bytes of ptr1 are found, respectively, to be less than, equal to, or greater than the first n bytes of ptr2.

Implementation:

The memcmp() function typically performs a byte-by-byte comparison of the memory blocks pointed to by ptr1 and ptr2.

It compares each byte in the memory blocks until either a difference is found or n bytes have been compared.

It then returns the result of the comparison based on the byte values encountered.

Example:

Program 1: Basic Usage

// Program for basic usage
#include<stdio.h> 
#include<string.h> 

int main() {
    char str1[] = "hello";
    char str2[] = "world";
    int result = memcmp(str1, str2, 5); // Compare first 5 characters
    if (result == 0) {
        printf("The strings are equal.\n");
    } else if (result < 0) {
        printf("The first string is less than the second.\n");
    } else {
        printf("The first string is greater than the second.\n");
    }
    return 0;
}	

Output:

The first string is less than the second.

Program 2: Using memcmp() for Array Comparison

// program for using memcmp() for array comparison
#include<stdio.h> 
#include<string.h> 

int main() {
    int arr1[] = {1, 2, 3};
    int arr2[] = {1, 2, 4};
    int result = memcmp(arr1, arr2, 3 * sizeof(int)); // Compare entire arrays
    if (result == 0) {
        printf("The arrays are equal.\n");
    } else if (result < 0) {
        printf("The first array is less than the second.\n");
    } else {
        printf("The first array is greater than the second.\n");
    }
    return 0;
}	

Output:

The first array is less than the second.

Program 3: Using memcmp() for Struct Comparison

// program for using memcmp() for struct comparison 
#include<stdio.h> 
#include<string.h> 

struct Point {
    int x;
    int y;
};

int main() {
    struct Point p1 = {1, 2};
    struct Point p2 = {1, 3};
    int result = memcmp(&p1, &p2, sizeof(struct Point)); // Compare entire structs
    if (result == 0) {
        printf("The structs are equal.\n");
    } else if (result < 0) {
        printf("The first struct is less than the second.\n");
    } else {
        printf("The first struct is greater than the second.\n");
    }
    return 0;
}

Output:

The first struct is less than the second.

These examples showcase the versatility of memcmp() in comparing strings, arrays, and structs, providing insight into its implementation and usage.