Help, Won't Run

[Ace01000]

This is my second attempt at a calculator, but my first at switch statements. I try to compile this, but i get a bulk of errors that make no sense to me, they all look rather similar, here is an example of the error: error C2784: 'std::basic_ostream<char,_Traits> &std::operator <<(std::basic_ostream<char,_Traits> &,unsigned char)' : could not deduce template argument for 'std::basic_ostream<char,_Elem> &' from 'std::istream'. I have a feeling that I may have messed up in many, many places in this code, so I can understand if it is to time consuming to help me. All help is greatly appriciated! :-)

#include <iostream>

using namespace std;

int main()
{

    int x, y, z;
    char math_operator, exit_app;
    int startover(char& exit_app);
    int calculation(int x, int y, int& z, char math_operator);


        cout << "(x ? y) - Please your first number followed by a space, then a legal math operator, followed by a space, then your second number. - (x ? y):  ";
        cin >> x >> math_operator >> y;

        while ((math_operator = '/') && (y == 0))
        {
            cout << "Error:  Cannot divide by zero." << endl;
            cout << "Please re enter a legal math operator ( Supported: Addition(+), Subtraction(-), Multiplication(*), Divide(/) ):  ";
            cin << math_operator;
        }

        while ((math_operator != '+') (math_operator != '-') (math_operator != '*') (math_operator != '/'))
        {
            cout << "You have not entered a supported math operator." << endl;
            cout << "Please enter a legal math operator:  ";
            cin >> math_operator;
        }

        calculation(x, y, z, math_operator);

        cout << x << " " << math_operator << " " << y << " = " << z << endl;

        startover(exit_app);
    

}



int calculation(int x, int y, int& z, char math_operator)
{
    
    switch (math_operator)
    {
    case '+': z = x + y; break;
    case '-': z = x - y; break;
    case '*': z = x * y; break;
    case '/': z = x / y; break;
    }

    return z;

}

int startover(char& exit_app)
{

    cout << "Thank you for using my program!" << endl;
    cout << "Would you like to start over? ( s = start over, q = quit ):  ";
    cin >> exit_app;

    switch (exit_app)
    {

    case 's': main()
    case 'q': cout << "Have a nice day!" << endl;
    
    }

    cin.get()

}

[Ancient Dragon]

>> cin << math_operator;

you used the output operator, not input. You meant this:
cin >> math_operator;

>> case 's': main()
Not allowed to call function main() in either c or c++. You will have to think of a different way to restart the program.