Question

So I have the following code:

char command;
cin >> command;
if ( command == 'P' ) {
    do_something();
}
if ( command == 'Q' ) {
    cout << "Exit\n";
    exit(0);
}
else {
    cout << "command= " command << endl; //use for debugging
    cout << "Non-valid input\n";
    exit(1);
}
cout << "exit at completion\n";
exit(0);
}

When I use input of P, my output after do_something() finishes is:

"output from do_something() function"
command= P
Non-valid input

My question is why do I still get the Non-valid input after do_something() is called in the first if statement? AKA why does the else still run when do_something() finishes?

Answer 1

You left out the else before the second if, which means that if command != 'Q' (which is true for P), the exit block will be executed.

You probably meant to do

if ( command == 'P' ) {
    do_something();
}
else if ( command == 'Q' ) { // Note the 'else'
    cout << "Exit\n";
    exit(0);
}
else {
    cout << "command= " command << endl; //use for debugging
    cout << "Non-valid input\n";
    exit(1);
}

That way, when the command is P, do_something will be called and all the rest will be skipped.