The Comma Operator: The value of a series of expressions is the value of the right most : Comma operator « Operators statements « C++ Tutorial

1. C++ Tutorial
2. Operators statements
3. Comma operator

#include <iostream>

using namespace std;

int main()
{
   long num1 = 0, num2 = 0, num3 = 0, num4 = 0;

   num4 = (num1 = 10, num2 = 20, num3 = 30);
   cout << num4;
   cout << endl;

   return 0;
}