C++ Example

#include <iostream>

using namespace::std;

void prototypefunction();

int main(){

    int choice;

    int list[1];

    list[0] = 1;
    list[1] = 2;

    int x = list[0];
    int y = list[1];
    int z = list[0] + list[1];

    system("cls");
    cout << "Simple C++ example's, coded by Harry Laurent" << endl;
    cout << "--------------------------------------------" << endl;
    cout << "1. Call a simple function to display a message." << endl;
    cout << "2. Simple variables math." << endl;
    cout << "3. Exit Program" << endl;

    cin >> choice;

    if(choice == 1){
         prototypefunction();
    }

    if(choice == 2){
         system("cls");
         cout << "The value of x + y = z, z = " << z << endl;
         system("pause");
         return main();
    }

    if(choice == 3){
         exit(1);
    }

    if(choice != 1 && choice != 2 && choice != 3 || choice == 'null'){
         system("cls");
         cout << "Invalid option, please try again." << endl;
         system("pause");

         return main();
    }

    return main();

}

void prototypefunction(){

     system("cls");
     cout << "This message is displayed using a function" << endl;
     system("pause");

     return;
}