implementation of merge sort in c

/* C program for Merge Sort */ #include<stdlib.h> #include<stdio.h>    // Merges two subarrays of arr[]. // First subarray is arr[l..m] // Second subarray is arr[m+1..r] void merge(int arr[], int l, int m, int r) {     int i, j, k;     int n1 = m - l + 1;     int n2 =  r - m;        /* create temp arrays */     int L[n1], R[n2];        /* Copy data to temp arrays L[] and R[] */     for (i = 0; i < n1; i++)         L[i] = arr[l + i];     for (j = 0; j < n2; j++)         R[j] = arr[m + 1+ j];        /* Merge the temp arrays back into arr[l..r]*/     i = 0; // Initial index of first subarray     j = 0; // Initial index of second subarray     k = l; // Initial index of merged subarray     while (i < n1 && j < n2)     {         if (L[i] <= R[j])         {             arr[k] = L[i];             i++;         }         else         {             arr[k] = R[j];             j++;         }         k++;     }        /* Copy the remaining elements of L[], if there        are any */     while (i < n1)     {         arr[k] = L[i];         i++;         k++;     }        /* Copy the remaining elements of R[], if there        are any */     while (j < n2)     {         arr[k] = R[j];         j++;         k++;     } }    /* l is for left index and r is right index of the    sub-array of arr to be sorted */ void mergeSort(int arr[], int l, int r) {     if (l < r)     {         // Same as (l+r)/2, but avoids overflow for         // large l and h         int m = l+(r-l)/2;            // Sort first and second halves         mergeSort(arr, l, m);         mergeSort(arr, m+1, r);            merge(arr, l, m, r);     } }    /* UTILITY FUNCTIONS */ /* Function to print an array */ void printArray(int A[], int size) {     int i;     for (i=0; i < size; i++)         printf("%d ", A[i]);     printf("\n"); }    /* Driver program to test above functions */ int main() {     int arr[] = {12, 11, 13, 5, 6, 7};     int arr_size = sizeof(arr)/sizeof(arr[0]);        printf("Given array is \n");     printArray(arr, arr_size);        mergeSort(arr, 0, arr_size - 1);        printf("\nSorted array is \n");     printArray(arr, arr_size);     return 0; }

Output:

Given array is
12 11 13 5 6 7

Sorted array is
5 6 7 11 12 13