C Program to Sort an Array using Merge Sort - Source Code, Output & Execution Flow

C Program to Sort an Array using Merge Sort

This tutorial explains c program to sort an array using merge sort with C source code, sample output, and step-by-step execution flow.

#include <stdio.h>
void merge(int a[], int l, int m, int r) {
    int i = l, j = m + 1, k = 0, temp[50];
    while (i <= m && j <= r) temp[k++] = (a[i] <= a[j]) ? a[i++] : a[j++];
    while (i <= m) temp[k++] = a[i++];
    while (j <= r) temp[k++] = a[j++];
    for (i = l, k = 0; i <= r; i++, k++) a[i] = temp[k];
}
void mergeSort(int a[], int l, int r) {
    if (l < r) {
        int m = (l + r) / 2;
        mergeSort(a, l, m);
        mergeSort(a, m + 1, r);
        merge(a, l, m, r);
    }
}
int main() {
    int a[] = {38, 27, 43, 3, 9}, i;
    mergeSort(a, 0, 4);
    for (i = 0; i < 5; i++) printf("%d ", a[i]);
    return 0;
}

3 9 27 38 43

Practice This Program

In this program, the input is read first when required, the core logic is applied step by step, and the final result is displayed using printf(). Follow the execution flow beside the code to understand how each statement contributes to the output.