Create methods with parameters

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A method is a named, reusable block of code that runs when you call it. Methods let you write logic once and use it as many times as you need, with different inputs each time.

Defining a method

You define a method with a return type, a name, and parentheses. Use void when the method doesn't return a value. The braces beneath make up the method body.

void Greet()
{
    Console.WriteLine("Hello, world!");
}

Greet(); // Output: Hello, world!

Method names use PascalCase by convention, and should describe what the method does.

Adding parameters

Parameters are named inputs listed inside the parentheses, each with its own type. They let you pass information into the method each time you call it.

void Greet(string name)
{
    Console.WriteLine($"Hello, {name}!");
}

Greet("Alex"); // Output: Hello, Alex!
Greet("Sam");  // Output: Hello, Sam!

You can define multiple parameters by separating them with commas.

void Greet(string name, string greeting)
{
    Console.WriteLine($"{greeting}, {name}!");
}

Greet("Alex", "Hi"); // Output: Hi, Alex!

Optional parameters with default values

You can give a parameter a default value by assigning it with = in the method definition. If the caller doesn't provide that argument, the default is used.

void Greet(string name, string greeting = "Hello")
{
    Console.WriteLine($"{greeting}, {name}!");
}

Greet("Alex");             // Output: Hello, Alex!
Greet("Alex", "Welcome");  // Output: Welcome, Alex!

Named arguments

You can also pass arguments by name, which makes your code easier to read, especially when a method has several parameters.

Greet(name: "Alex", greeting: "Welcome");

Named arguments can appear in any order, but any positional arguments must still come first.