Menu solution

[luckielordie]

Hi im reletivly new to programming in C++ and this is my first attempt at trying to make a half decent project for myself. I have tried to incorperate the calling of functions , arithmatic, if statements and loops to help me gain a better understanding of the syntax and the language.
Here is my problem, i have tried to put in a menu option to the program ( its all in console for now) but when you run the code it seems to miss out the loop while statement all together, i think it might be the way i have tried to pass over the value for the global variable selection but i have no idea how to solve this as i have tried many different solutions to no prevail.

#include <iostream>
#include <string>
#include <cmath>
using namespace std;

# define g 9.81
int selection = 0;
int menu()
{
    selection = a + b;
    cout << "1. The Vertical Velocity of an object after a determined amount of time" << endl;
    cout << endl;
    cout << "2. The vertical Displacement of an object after a determined amount of time" << endl;
    cout << endl;
    cout << "3. The Horozontal Displacement after a determined amount of time and off of\n   a certain height" << endl;
    cout << endl;
    cout << "4. Exit the program" << endl << endl;
    cout << "Please select the function you would like to perform : ";
    cin >> selection;
    return (selection);
}

double Vertv()
{
    cout << "Test Option 1 success ! ";
}

double Vertx()
{
    cout << "Test Option 2 success ! ";
}

double Horozx()
{
    cout << "Test Option 3 success ! ";
}

int end()
{
    cout << "Test Option 4 success ! ";
}

int main ()
{
    int n = 0;
    cout << "Welcome to the C++ Projectile Motion Calculator !" << endl;
    cout << endl;
    cout << "This Program can calculate many things about simple \nProjectile motion please select an option below "<< endl;
    cout << endl;
    cout << "---------------------------------------------------";
    cout << endl;
    do {
    if (selection = 1 )
    {
        n = 1;
        Vertv();
    }
    else if (selection = 2)
    {
        n = 1;
        Vertx();
    }
    else if (selection = 3)
    {
        n = 1;
        Horozx();
    }
    else if (selection = 4)
    {
        n = 1;
        end();
    }
    else
    {
        cout << "You have not entered a valid selection please try again" << endl;
        cout << "Please select the function you would like to perform : ";
        cin >> selection;
    }
    } while (n = 0);
       


    system("pause");
        return 0;
}

Any help would be much apprieciated
luckielordie

[Dufresne]

Comparison operator is not = , it's ==
so you better replace = with ==

[kikirikou]

Look my friend, i didn't understood exactly what you are trying to do,but i made some simple changes to your code.First of all your functions Vertv() ,Vertx() are declared as double,which means that they must return a double variable.You selected just to print something inside them,so you beter declared thes as void. Also since you have 4 choises i would suggest swithc instead of if else

take a look at this :

#include<iostream>
using namespace std;


void Vertv()
{
    cout << "Test Option 1 success ! \n";
}

void Vertx()
{
    cout << "Test Option 2 success ! \n";
}

void Horozx()
{
    cout << "Test Option 3 success ! \n";
}

void end()
{
    cout << "Test Option 4 success ! \n";
}


void menu()
{
    char choise;
    int n=0;
    
    
    do
    {
        cout<<"Give me a choise  \n";
        cout<<"a----> The Vertical Velocity of an object after a determined amount of time \n";
        cout<<"b----> The vertical Displacement of an object after a determined amount of time \n";
        cout<<"c----> The Horozontal Displacement after a determined amount of time and off of   a certain height \n\n";
        
        cout<<"choise:\n";
        cin>>choise;

        switch(choise)
        {
            case('a'):
                Vertv();
                n=1;

                break;
            case('b'):
                Vertx();
                n=1;

                break;
            case('c'):
                Horozx();
                n=1;

                break;
            default:
                cout << "\n You have not entered a valid selection please try again \n";
                cout << "Please select the function you would like to perform : \n";

                break;
        }
    }while(n!=1);

}



int main()
{
    menu();

    return 0;
}

[luckielordie]

Thanks guys, i got up first thing this morning and had a go at your solutions. The reason the functions Horozx, Vertx and Vertv we're doubles is that they will output a value when the code is finished but your right for the purpose of testing those phrases they should have been void.

Thankyou all, i hope to finish the rest of the code at some point today i'll post it somewhere so that you can all see the finished result
luckielordie