5.4 Methods within classes

Let’s go over methods within classes in C# — an essential concept in object-oriented programming.

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📌 1. What Are Methods in Classes?

• A method is a function defined inside a class.

• It represents behavior or actions that an object of the class can perform.

• Methods can access fields and properties of the class.

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📌 2. Basic Syntax

[access_modifier] [return_type] MethodName([parameters])
{
    // Method body
}

• access_modifier → public, private, etc. (who can access the method)

• return_type → data type the method returns (void if nothing is returned)

• parameters → optional input values

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📌 3. Example: Method in a Class

public class Person
{
    public string Name;
    public int Age;
 
    // Method
    public void Greet()
    {
        Console.WriteLine($"Hello, my name is {Name} and I am {Age} years old.");
    }
}
 
// Usage
Person person = new Person();
person.Name = "Alice";
person.Age = 25;
person.Greet();  // Hello, my name is Alice and I am 25 years old.

• Greet() is a method inside the class

• It can access Name and Age of the object

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📌 4. Methods with Parameters and Return Values

public class Calculator
{
    public int Add(int a, int b)
    {
        return a + b;
    }
}
 
// Usage
Calculator calc = new Calculator();
int result = calc.Add(5, 3); // 8

• Add(int a, int b) has parameters

• Returns a value using return

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📌 5. Static vs Instance Methods. Also See Difference Between Instance and Static Methods

1. Instance Methods

   • Called on an object

   • Can access instance fields and properties

public void DisplayName()
{
    Console.WriteLine(Name);
}

2. Static Methods

   • Belong to the class itself, not an object

   • Cannot access instance fields directly

public static int Multiply(int a, int b)
{
    return a * b;
}
 
// Usage
int result = Calculator.Multiply(2, 3); // 6

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📌 6. Access Modifiers for Methods

Modifier	Description
public	Accessible anywhere
private	Accessible only inside the class
protected	Accessible in derived classes
internal	Accessible within the same assembly
protected internal	Accessible in derived classes or same assembly

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📌 7. Method Overloading

• Methods in a class can have same name but different parameters

public int Add(int a, int b) => a + b;
public double Add(double a, double b) => a + b;

• Compiler picks the correct method based on arguments provided

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📌 8. Summary

Concept	Description
Method	Function inside a class representing behavior
Instance vs Static	Instance = called on object; Static = called on class
Parameters	Input values for the method
Return Type	Value returned by the method (void if none)
Overloading	Multiple methods with same name but different parameters
Access Modifier	Controls visibility (public, private, etc.)

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✅ Tip:

• Methods should do one specific task.

• Use instance methods for object-specific behavior, static methods for general utilities.

• Combine methods with properties and fields to make classes powerful and encapsulated.