Create arrays A, B of size 3, C of size 6, merge A and B into C.

Learn how to merge two arrays into a third array in C

merge_arrays.c

#include <stdio.h>

int main() {
    int A[3], B[3], C[6];
    int i;

    // Input elements of array A
    printf("Enter 3 elements of array A:\n");
    for(i = 0; i < 3; i++) {
        printf("A[%d]: ", i);
        scanf("%d", &A[i]);
    }

    // Input elements of array B
    printf("\nEnter 3 elements of array B:\n");
    for(i = 0; i < 3; i++) {
        printf("B[%d]: ", i);
        scanf("%d", &B[i]);
    }

    // Merge A into C
    for(i = 0; i < 3; i++) {
        C[i] = A[i];
    }

    // Merge B into C
    for(i = 0; i < 3; i++) {
        C[i + 3] = B[i];
    }

    // Display merged array C
    printf("\nMerged array C:\n");
    for(i = 0; i < 6; i++) {
        printf("C[%d] = %d\n", i, C[i]);
    }

    return 0;
}

🧾 Step-by-Step Explanation

🔹 Step 1: Include Header File

#include <stdio.h>

This header provides:

• printf() for output display
• scanf() for user input
• Standard I/O functions

🔹 Step 2: Declare Arrays and Variable

int A[3], B[3], C[6];
int i;

• A[3] and B[3]: Input arrays (3 elements each)
• C[6]: Output array for merged result
• i: Loop counter for array operations

🔹 Step 3: Input Elements in Array A

for(i = 0; i < 3; i++) {
    printf("A[%d]: ", i);
    scanf("%d", &A[i]);
}

• Prompts user for 3 values
• Stores them in array A
• Uses %d format for integers

🔹 Step 4: Input Elements in Array B

for(i = 0; i < 3; i++) {
    printf("B[%d]: ", i);
    scanf("%d", &B[i]);
}

• Same process as Step 3
• Stores values in array B
• Maintains parallel indexing

🔹 Step 5: Merge Array A into C

for(i = 0; i < 3; i++) {
    C[i] = A[i];
}

• Copies A[0] to C[0]
• Copies A[1] to C[1]
• Copies A[2] to C[2]

🔹 Step 6: Merge Array B into C

for(i = 0; i < 3; i++) {
    C[i + 3] = B[i];
}

• Copies B[0] to C[3]
• Copies B[1] to C[4]
• Copies B[2] to C[5]
• Uses index shifting (i + 3)

🔹 Step 7: Display Merged Array C

for(i = 0; i < 6; i++) {
    printf("C[%d] = %d\n", i, C[i]);
}

• Prints all 6 elements of C
• Shows index and value for each
• Uses \n for newlines

🧪 Sample Output

Enter 3 elements of array A:
A[0]: 10
A[1]: 20
A[2]: 30

Enter 3 elements of array B:
B[0]: 40
B[1]: 50
B[2]: 60

Merged array C:
C[0] = 10
C[1] = 20
C[2] = 30
C[3] = 40
C[4] = 50
C[5] = 60

📌 Key Concepts Covered

Array Declaration

Creating fixed-size collections of elements with int arr[size]

Array Merging

Combining two arrays by copying elements sequentially

Index Shifting

Using C[i + 3] to place elements after existing ones

for Loop

Iterating through arrays with precise index control

I/O Operations

Using printf() and scanf() for console interaction