class Program { static void Main(string[] args) { int arg; // Passing by value. // The value of arg in Main is not changed. arg = 4; squareVal(arg); Console.WriteLine(arg); // Output: 4 // Passing by reference. // The value of arg in Main is changed. arg = 4; squareRef(ref arg); Console.WriteLine(arg); // Output: 16 } static void squareVal(int valParameter) { valParameter *= valParameter; } // Passing by reference static void squareRef(ref int refParameter) { refParameter *= refParameter; } }