Methods and Parameters

Part of the Object Oriented Programming section of Coddy's C# journey — lesson 5 of 70.

Methods define actions that an object can perform. Parameters allow you to pass data into methods, and return types specify what data comes back.

Define a method with parameters and a return type

public class Calculator
{
    public int Add(int a, int b)
    {
        return a + b;
    }
}

Method with multiple parameters

public class Calculator
{
    public int Add(int a, int b)
    {
        return a + b;
    }
    
    public double Multiply(double x, double y)
    {
        return x * y;
    }
}

Method with no return value (void)

public class Printer
{
    public void PrintMessage(string message)
    {
        Console.WriteLine(message);
    }
}

Calling methods with arguments

Calculator calc = new Calculator();
int result = calc.Add(5, 3);
Console.WriteLine(result);  // Output: 8

double product = calc.Multiply(2.5, 4.0);
Console.WriteLine(product);  // Output: 10

Method with string parameter and return

public class Greeter
{
    public string CreateGreeting(string name)
    {
        return $"Hello, {name}!";
    }
}

Greeter greeter = new Greeter();
string message = greeter.CreateGreeting("Alice");
Console.WriteLine(message);  // Output: Hello, Alice!

Parameters are variables that receive values when the method is called. The return type (like int, string, or void) specifies what kind of data the method gives back. Use void when a method doesn't return anything.

Challenge

Medium

Create three methods in the Calculator class:

Add - takes two integers and returns their sum
Subtract - takes two integers and returns their difference (first - second)
Multiply - takes two integers and returns their product

Cheat sheet

Methods define actions that an object can perform. Parameters allow you to pass data into methods, and return types specify what data comes back.

Define a method with parameters and a return type:

public class Calculator
{
    public int Add(int a, int b)
    {
        return a + b;
    }
}

Method with no return value (void):

public class Printer
{
    public void PrintMessage(string message)
    {
        Console.WriteLine(message);
    }
}

Calling methods with arguments:

Calculator calc = new Calculator();
int result = calc.Add(5, 3);
Console.WriteLine(result);  // Output: 8

Method with string parameter and return:

public class Greeter
{
    public string CreateGreeting(string name)
    {
        return $"Hello, {name}!";
    }
}

Try it yourself

using System;

class Program
{
    static void Main()
    {
        int num1 = int.Parse(Console.ReadLine());
        int num2 = int.Parse(Console.ReadLine());
        
        Calculator calc = new Calculator();
        
        Console.WriteLine($"Add: {calc.Add(num1, num2)}");
        Console.WriteLine($"Subtract: {calc.Subtract(num1, num2)}");
        Console.WriteLine($"Multiply: {calc.Multiply(num1, num2)}");
    }
}