The if statement

An if statement selects a statement for execution based on the value of a boolean expression. An if statement may optionally include an else clause that executes if the boolean expression is false.
The example
using System;
class Test
{
    static void Main(string[] args) {
        if (args.Length == 0)
            Console.WriteLine("No arguments were provided");
        else
            Console.WriteLine("Arguments were provided");
    }
}
shows a program that uses an if statement to write out two different messages depending on whether command-line arguments were provided or not.