Вызов функции. Перенос переменной

#include <iostream> 
#include <fstream> //files out or in libraries. 
using namespace std;
int optmenu(char *menu)
{
cout << "Please select one of the following options:\n" << endl;
cout << "1.Write numbers to file\n" << endl;
cout << "2.Read numbers from file\n" << endl;
cout << "3.Add the numbers and display the result\n" << endl;
cout << "4.Exit.\n" << endl;
cin >> menu;
return (0);
}
int main() 
{
char menu;
int num1, num2;
ifstream fin;//File input.
ofstream fout;//File output.
optmenu(&menu);
    switch (menu)
    {
        case '1':   
        fout.open ("num.txt");
            if (fout.fail())
            {
            cout << "Error opening file, maybe file is missing!" << endl;
            }
            cout << "Please enter 2 integer numbers\n" << endl;
            cout << "The first number is:" << endl;
            cin >> num1;
            cout << "\nThe second number is:" << endl;
            cin >> num2;
            fout << num1 << "\n" << num2 << "\n";   
        fout.close ();
        break;
        case '2':   
        fin.open ("num.txt");
            if (fin.fail())
            {
            cout << "Error opening file, maybe file is missing!" << endl;
            }
            while (!fin.eof())
            {
            fin >> num1 >> num2;
            }
            cout << "Data input completed!\n" << endl;
            cout << "The numbers are " << num1 << " and "<< num2 << endl; 
        fin.close ();
        break;
        case '3':
        fin.open ("num.txt");
            if (fin.fail())
            {
            cout << "Error opening file, maybe file is missing!" << endl;
            }
            while (!fin.eof())
            {
            fin >> num1 >> num2;
            }
            cout << "The addition of the 2 integer numbers is " << num1 + num2 << endl;             
        fin.close ();
        break;
        default:
            exit(0);
    }
system("Pause"); 
return (0);
}

int optmenu(char *menu)
{
cout << "Please select one of the following options:\n" << endl;
cout << "1.Write numbers to file\n" << endl;
cout << "2.Read numbers from file\n" << endl;
cout << "3.Add the numbers and display the result\n" << endl;
cout << "4.Exit.\n" << endl;
cin >> *menu;//////////////////////////////////////
return (0);
}