Changed the input style

Merge sort in C++

/*
 * File:   main.cpp
 * Author: emrahgunduz
 *
 * Created on March 12, 2013, 3:57 PM
 */

#include <iostream>

using namespace std;

void merge(int*, int*, int, int, int);

void mergesort(int *a, int*b, int start, int end) {
  int halfpoint;
  if (start < end) {
    halfpoint = (start + end) / 2;
    mergesort(a, b, start, halfpoint);
    mergesort(a, b, halfpoint + 1, end);
    merge(a, b, start, halfpoint, end);
  }
}

void merge(int *a, int *b, int start, int halfpoint, int end) {
  int h, i, j, k;
  h = start;
  i = start;
  j = halfpoint + 1;

  while ((h <= halfpoint) && (j <= end)) {
    if (a[h] <= a[j]) {
      b[i] = a[h];
      h++;
    } else {
      b[i] = a[j];
      j++;
    }
    i++;
  }
  if (h > halfpoint) {
    for (k = j; k <= end; k++) {
      b[i] = a[k];
      i++;
    }
  } else {
    for (k = h; k <= halfpoint; k++) {
      b[i] = a[k];
      i++;
    }
  }

  // Write the final sorted array to our original one
  for (k = start; k <= end; k++) {
    a[k] = b[k];
  }
}

int main(int argc, char** argv) {
  int num;
  cout << "How many numbers do you want to sort: ";
  cin >> num;
  int a[num];
  int b[num];
  for (int i = 0; i < num; i++) {
    cout << (i + 1) << ": ";
    cin >> a[i];
  }

  // Start merge sort
  mergesort(a, b, 0, num - 1);

  // Print the sorted array
  cout << endl;
  for (int i = 0; i < num; i++) {
    cout << a[i] << " ";
  }
  cout << endl;

  return 0;
}