# C Program for Iterative Merge Sort

Following is a typical recursive implementation of Merge Sort that uses last element as pivot.

 `/* Recursive C program for merge sort */` `#include ` `#include ` ` `  `/* Function to merge the two haves arr[l..m] and arr[m+1..r] of array arr[] */` `void` `merge(``int` `arr[], ``int` `l, ``int` `m, ``int` `r); ` ` `  `/* 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) { ` `        ``int` `m = l + (r - l) / 2; ``// Same as (l+r)/2 but avoids overflow for large l & h ` `        ``mergeSort(arr, l, m); ` `        ``mergeSort(arr, m + 1, r); ` `        ``merge(arr, l, m, r); ` `    ``} ` `} ` ` `  `/* Function to merge the two haves arr[l..m] and arr[m+1..r] of array arr[] */` `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; ` `    ``j = 0; ` `    ``k = l; ` `    ``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++; ` `    ``} ` `} ` ` `  `/* 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); ` ` `  `    ``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
```

Please refer complete article on Iterative Merge Sort for more details!

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