C# Example of Delegate as Method Parameter

Delegate is a type, so it can be used as Method Parameter. This is shown using code example in post.

We define a delegate for arithmetic operations. This delegate is used as first parameter of Calculate method. The parameter can accept a method definition as argument. We can use Lambda expression for method also.

    public delegate int ArithmeticOperation(int number1, int number2);
    static class Calculator
    {
        public static int Calculate(ArithmeticOperation operation, int number1, int number2)
        {
            try
            {
                int total = operation.Invoke(number1, number2);
                return total;
            }
            catch (DivideByZeroException ex)
            {
                Console.WriteLine(ex.Message);
                return 0;
            }
        }
    }

Lambda expression is used as delegate argument for Calculate method in client Program class Main method.

    class Program
    {
        static void Main(string[] args)
        {
            int sum = Calculator.Calculate((x, y) => (x + y), 100, 5);
            int difference = Calculator.Calculate((x, y) => (x - y), 100, 5);
            int product = Calculator.Calculate((x, y) => (x * y), 100, 5);
            int division = Calculator.Calculate((x, y) => (x / y), 100, 5);

            Console.WriteLine("+ Result is " + sum);
            Console.WriteLine("- Result is " + difference);
            Console.WriteLine("* Result is " + product);
            Console.WriteLine("/ Result is " + division);
            Console.ReadLine();
        }
    }

Result:

+ Result is 105

- Result is 95

* Result is 500

/ Result is 20

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