Question

In the journey to learning C++ I’m learning through the C++ Manual that’s on the actual website. I’m using DevC++ and have hit a problem, not knowing whether its the compiler error or not.

I was going through this code bit by bit typing it in myself, as I feel it’s more productive, and adding my own stuff that I’ve learnt from the examples, then I got to initialising variables. This is the code that is in the C++ manual

#include <iostream>

using namespace std;
int main ()
{
    int a=5;     // initial value = 5
    int b(2);    // initial value = 2
    int result;  // initial value undetermined

    a = a + 3;
    result = a - b;
    cout << result;

    return 0;
}

This is popping up a compiler error saying "Multiple definitions of "Main""
Now this is on the actual C++ page so I’m guessing it’s a compiler error.

Could someone please point me in the right direction as to why this is happening and what is the cause for this error?

Answer 1

Multiple definitions of “main” suggests that you have another definition of main. Perhaps in another .c or .cpp file in your project. You can only have one function with the same name and signature (parameter types). Also, main is very special so you can only have one main function that can be used as the entry point (has either no parameters, one int, or an int and a char**) in your project.

P.S. Technically this is a linker error. It’s a subtle difference, but basically it’s complaining that the linker can’t determine which function should be the entry point, because there’s more than one definition with the same name.