merging two unsorted lists from two files into a third file into sorted from

 #include <iostream>

#include <fstream>

using namespace std;

void swap(int &size, int arra[])

{

    int i, max1;

    for (i = 0; i < size; i++)

    {

        for (int j1 = i + 1; j1 < size; j1++) // checks greater between previous and next index and swaps the greater with smaller

        {

            if (arra[j1] < arra[i])

            {

                max1 = arra[i];

                arra[i] = arra[j1];

                arra[j1] = max1;

            }

        }

    }

}

void sortedMerge(int a[], int b[], int res[],

                 int n, int m) // Merge two arrays in unsorted manner

{

    // Concatenate two arrays

    int i = 0, j = 0, k = 0;

    while (i < n)

    {                  // iterate in first array

        res[k] = a[i]; // put each element in res array

        i += 1;

        k += 1;

    }

    while (j < m)

    {                  // iterate in the second array

        res[k] = b[j]; // put each element in res array

        j += 1;

        k += 1;

    }

}

int main()

{

    ifstream o1, o2;

    ofstream o3;

    int size1, size2, max1, max2;

    cout << "enter number of integers in first file\n";

    cin >> size1;

    cout << "enter number of integers in second file\n";

    cin >> size2;

    int arr[100];

    int i = 0;

    int arr1[100];

    int j = 0;

    int n1, n2;

    o1.open("newfile1.txt");

    o2.open("newfile2.txt");

    o3.open("newfile3.txt");

    while (o1 >> n1) // executes only if o1 is not at eof

    {

        arr[i] = n1;

        i++;

    }

    o1.close();

    swap(size1, arr);

    for (i = 0; i < size1; i++)

    {

        cout << "\n "

             << "arr-" << i + 1 << "  " << arr[i] << '\n';

    }

    while (o2 >> n2) // executes only if o2 is not at eof

    {

        arr1[j] = n2;

        j++;

    }

    o2.close();

    swap(size2, arr1);

    for (j = 0; j < size2; j++)

    {

        cout << "\n "

             << "arr(1)" << j + 1 << " " << arr1[j] << "\n";

    }

    int size3 = size1 + size2;

    int res[size3];                    // create res array to Concatenate both the array

    sortedMerge(arr, arr1, res, size1, size2); // call function to append and sort

    swap(size3, res);

    cout << "The sorted array is: "<<endl;

    for (int k = 0; k < size3; k++)

        cout << " " << res[k] << " ";

    cout << "\n";

   

    for ( int c = 0; c < size3; c++)

    {

        o3<<res[c]<<" ";

    }

   

    o3.close();

    return 0;

}