C Program to Merge Two Arrays Using Pointers

Introduction

Merging two arrays involves combining the elements of two arrays into a single array. In C, you can use pointers to efficiently traverse the two arrays and copy their elements into a third array. This guide will show you how to write a C program to merge two arrays using pointers.

Example:

• Input: Array 1 [1, 3, 5], Array 2 [2, 4, 6]
• Output: Merged array [1, 2, 3, 4, 5, 6]

Problem Statement

Create a C program that:

• Takes two arrays of integers as input from the user.
• Uses pointers to merge the two arrays into a third array.
• Displays the merged array.

Solution Steps

1. Include the Standard Input-Output Library: Use #include <stdio.h> for standard input-output functions.
2. Declare the Arrays and Pointer Variables: Declare integer arrays to store the elements and pointers for accessing and manipulating the elements.
3. Input the Array Elements: Use loops to take input for the elements of the two arrays from the user.
4. Merge the Arrays Using Pointers: Use pointers to copy the elements of the two arrays into a third array.
5. Display the Merged Array: Use printf to display the merged array.

C Program to Merge Two Arrays Using Pointers

#include <stdio.h>

int main() {
    // Step 2: Declare the arrays and pointer variables
    int arr1[100], arr2[100], merged[200];
    int n1, n2, n3, i;
    int *ptr1, *ptr2, *ptr_merged;

    // Step 3: Input the number of elements and the array elements for the first array
    printf("Enter the number of elements in the first array: ");
    scanf("%d", &n1);

    printf("Enter the elements of the first array: ");
    for (i = 0; i < n1; i++) {
        scanf("%d", &arr1[i]);
    }

    // Input the number of elements and the array elements for the second array
    printf("Enter the number of elements in the second array: ");
    scanf("%d", &n2);

    printf("Enter the elements of the second array: ");
    for (i = 0; i < n2; i++) {
        scanf("%d", &arr2[i]);
    }

    // Step 4: Merge the arrays using pointers
    ptr1 = arr1;        // Pointer to the first array
    ptr2 = arr2;        // Pointer to the second array
    ptr_merged = merged;  // Pointer to the merged array

    // Copy elements from the first array to the merged array
    for (i = 0; i < n1; i++) {
        *ptr_merged = *ptr1;
        ptr1++;
        ptr_merged++;
    }

    // Copy elements from the second array to the merged array
    for (i = 0; i < n2; i++) {
        *ptr_merged = *ptr2;
        ptr2++;
        ptr_merged++;
    }

    n3 = n1 + n2;  // Total number of elements in the merged array

    // Step 5: Display the merged array
    printf("Merged array: ");
    for (i = 0; i < n3; i++) {
        printf("%d ", merged[i]);
    }
    printf("\n");

    return 0;  // Return 0 to indicate successful execution
}

Explanation

Step 2: Declare the Arrays and Pointer Variables

• The integer arrays arr1 and arr2 are declared to store the elements of the two input arrays.
• The array merged is declared to store the elements of the merged array.
• The pointers ptr1, ptr2, and ptr_merged are used to traverse and copy the elements from the two input arrays to the merged array.

Step 3: Input the Array Elements

• The program prompts the user to enter the number of elements in the first array and stores this value in n1.
• A for loop is used to take input for each element of the first array.
• Similarly, the program prompts the user to enter the number of elements in the second array and stores this value in n2.
• Another for loop is used to take input for each element of the second array.

Step 4: Merge the Arrays Using Pointers

• The pointer ptr1 is initialized to point to the first element of the first array (arr1), and ptr2 is initialized to point to the first element of the second array (arr2).
• The pointer ptr_merged is initialized to point to the first element of the merged array (merged).
• A for loop is used to copy each element from the first array into the merged array using the pointers ptr1 and ptr_merged.
• Another for loop is used to copy each element from the second array into the merged array using the pointers ptr2 and ptr_merged.
• The total number of elements in the merged array is stored in n3.

Step 5: Display the Merged Array

• The program uses a for loop to display the elements of the merged array.

Return 0

• The return 0; statement indicates that the program executed successfully.

Output Example

Example Output:

Enter the number of elements in the first array: 3
Enter the elements of the first array: 1 3 5
Enter the number of elements in the second array: 3
Enter the elements of the second array: 2 4 6
Merged array: 1 3 5 2 4 6

Conclusion

This C program demonstrates how to merge two arrays using pointers. It covers basic concepts such as pointer manipulation, array traversal, and array merging, making it a useful example for beginners learning C programming.