Defining Methods in C#

A method in C# is a named, reusable block of code with a declared return type and parameter list:

static int Add(int a, int b)
{
    return a + b;
}

int result = Add(3, 4); // 7

Every method states its return type up front (int here), or void if it doesn't return anything:

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

Expression-bodied methods

For a method that's just a single expression, C# offers a shorter syntax using =>:

static int Add(int a, int b) => a + b;

This is functionally identical to the version with { return a + b; } — it's purely a more compact way to write a one-line method, and you'll see it used heavily for small helpers and property getters alike.

Parameters: by value vs. by reference

By default, arguments are passed by value — the method gets a copy:

static void Increment(int x)
{
    x++;
}

int number = 5;
Increment(number);
Console.WriteLine(number); // still 5 -- the copy was incremented, not the original

To let a method modify the caller's variable, use ref:

static void Increment(ref int x)
{
    x++;
}

int number = 5;
Increment(ref number);
Console.WriteLine(number); // 6

ref must appear at both the method definition and the call site — C# deliberately makes this visible at the call site so it's never a silent surprise.

out parameters

out is similar to ref but is meant for a method to produce a value the caller didn't need to initialize first — the classic example is TryParse:

static bool TryDivide(int a, int b, out int result)
{
    if (b == 0)
    {
        result = 0;
        return false;
    }
    result = a / b;
    return true;
}

if (TryDivide(10, 2, out int quotient))
{
    Console.WriteLine(quotient); // 5
}

This "try" pattern — return a bool for success, hand back the real value via out — is idiomatic C# and shows up throughout the standard library (int.TryParse, Dictionary.TryGetValue, and more). It lets you handle a fallible operation without exceptions for what's really just an expected outcome, not an error.