C Program to Merge Two Arrays

1. Introduction

Merging arrays is a common operation in data manipulation. It allows you to combine two arrays into a single array. This tutorial covers a C program that accomplishes this task. We will walk through each step to ensure you have a deep understanding.

2. Program Overview

Our program will perform the following steps:

1. Get the size of the two arrays and their respective elements from the user.

2. Merge these arrays into a third array.

3. Display the merged array.

3. Code Program

#include <stdio.h>  // Standard Input/Output library

int main() {  // Starting the main function.
    int a[50], b[50], merged[100], n1, n2, i;

    // Asking user to input the size and elements of the first array.
    printf("Enter the size of the first array: ");
    scanf("%d", &n1);
    printf("Enter %d elements for the first array:\n", n1);
    for(i = 0; i < n1; i++) {
        scanf("%d", &a[i]);

    // Asking user to input the size and elements of the second array.
    printf("Enter the size of the second array: ");
    scanf("%d", &n2);
    printf("Enter %d elements for the second array:\n", n2);
    for(i = 0; i < n2; i++) {
        scanf("%d", &b[i]);

    // Merging the two arrays.
    for(i = 0; i < n1; i++) {
        merged[i] = a[i];  // First array elements.
    for(i = 0; i < n2; i++) {
        merged[n1+i] = b[i];  // Second array elements.

    // Displaying the merged array.
    printf("Merged array is:\n");
    for(i = 0; i < n1 + n2; i++) {
        printf("%d ", merged[i]);

    return 0;  // Ending the program.


First array size: 3, Elements: 1, 2, 3
Second array size: 2, Elements: 4, 5
The program will display:
Merged array is:
1 2 3 4 5

4. Step By Step Explanation

1. Header Files: We begin by including the stdio.h header, which provides functions for standard input and output.

2. Variable Declaration:

  • Arrays a and b store the elements of the first and second arrays, respectively.
  • Array merged is for the merged array.
  • Variables n1 and n2 will store the sizes of the two arrays.

3. User Input:

  • The user is prompted to provide the size and elements for both arrays.

4. Merging Process:

  • Elements from the first array a are added to the merged array.
  • Elements from the second array b are appended to the merged array, starting from the index immediately after the last element of the first array.

5. Displaying the Merged Array: We loop through the merged array and print its elements.

Combining arrays in this way allows you to concatenate data from different sources or simply manage data more efficiently.