Just to expand on SlyMaelstrom's reply - the const qualifier has nothing to do with the return type of the function, be it "void", "int" or some other type. You can also have a const function which returns a const int, then you'd use the const keyword twice in the function declaration.
this example might be a good illustration (this deliberately won't compile.)
Code:
#include <iostream>
using namespace std;
class MyClass
{
int i;
public:
MyClass() : i(5) {}
int geti() { return i; }
// geti() isn't const, it is free to modify the object.
};
int main()
{
const MyClass MyObj;
int x = MyObj.geti(); // ERROR!! geti() may potentially modify MyObj.
cout << x;
}
the compiler needs "const" after geti() as a promise that you are not going to modify MyObj.