Thread: What is the difference between operator and function?

They are both functions (when it comes to operator overloading), except that operators are normally called with a different syntax. For class objects it is also possible to call overloaded operators with function-syntax:

Code:

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


int main()
{
    string a = "Hello ", b = "world";
    string c = operator+(a, b);
    cout << c;
    return 0;
}

sizeof is a slightly different operator as it is evaluated at compile time, and by the way - you don't need to use () around the type. You can use it without any brackets, or put the brackets around sizeof instead (unless in a compound statement brackets are needed).

In addition, there is also operator() that allows you to "call" an object as if it was a function

operator list is fixed, you cannot create new operator or change the name of the existing, or change the parameter list

functions could be added freely, you can create funtion with arbitrary name, list of parameters and return values