Methods Introduction

A method is a named block of code that does something. You've already been using one — Main. Now let's write your own.

Defining a Method

A method has a return type, a name, parentheses for parameters, and a body. If it doesn't return anything, use void.

using System;

class Program {
  static void SayHello() {
    Console.WriteLine("Hello!");
  }
  
  static void Main() {
    SayHello();
    SayHello();
  }
}
    

Return Types

Use return to send a value back to the caller. The method's return type must match what you return.

using System;

class Program {
  static int Add(int a, int b) {
    return a + b;
  }
  
  static void Main() {
    int result = Add(3, 4);
    Console.WriteLine(result);
  }
}
    

The static Keyword

static means the method belongs to the class itself, not to an instance. Since Main is static, any method it calls directly must also be static.

using System;

class Program {
  static int Square(int x) {
    return x * x;
  }
  
  static void Main() {
    Console.WriteLine(Square(5));
    Console.WriteLine(Square(12));
  }
}
    

Early Return

You can exit a method early with return. Useful for guard clauses — check for invalid input at the top and bail out.

using System;

class Program {
  static string CheckAge(int age) {
    if (age < 0) return "Invalid";
    if (age >= 18) return "Adult";
    return "Minor";
  }
  
  static void Main() {
    Console.WriteLine(CheckAge(20));
    Console.WriteLine(CheckAge(-5));
  }
}