Generics in C# – Writing Reusable Code

1Writing Reusable Code with Generics

Hi friends, in this article we will learn generics in C#. Generics allow us to write reusable code that works with different data types. Instead of creating separate classes or methods for integers, strings and other types, we can use one generic implementation. Generics provide type safety, reduce duplicate code and avoid unnecessary type conversions. They are widely used in collections, repositories, APIs and enterprise applications.

2Think About a Reusable Storage Box

Imagine a storage box. Sometimes you store books, sometimes toys and sometimes documents. You need the same storage behaviour, but the stored item changes.

Generics work in a similar way. We create one generic class and decide its data type when creating an object. The same class can store an integer, string or another type safely.

3Understand Generic Types

Generic Class

A generic class uses a type parameter such as T. The actual type is supplied when creating an object.

Generic Method

A generic method defines its own type parameter. It can work with different types without rewriting the method.

Type Safety

The compiler checks the type during compilation. This helps prevent invalid assignments and reduces runtime casting errors.

Generic Constraints

Constraints restrict which types can be used. For example, where T : class requires a reference type.

4Build Your First Generic Class

Let's create a reusable Box class. We will store an integer and a string using the same class. We will also create a generic method.

using System;

class Box<T>
{
    public T Value { get; set; }
}

class Program
{
    static void PrintValue<T>(T value)
    {
        Console.WriteLine(value);
    }

    static void Main()
    {
        var numberBox = new Box<int>();
        numberBox.Value = 100;

        var textBox = new Box<string>();
        textBox.Value = "CSharp";

        PrintValue(numberBox.Value);
        PrintValue(textBox.Value);
    }
}

Here, T becomes int for numberBox and string for textBox. The compiler checks each assignment. PrintValue also detects the type from the supplied argument.

5Check the Program Result

100
CSharp

The same Box class stores two different types. The generic method prints both values without requiring separate methods.

6Watch Generic Types in Action

Follow how the type parameter T becomes int and then string. Both objects use the same generic class.

7Why Generics Matter

Generics help us write reusable and type-safe code. They reduce duplication and make applications easier to maintain. Collections such as List and Dictionary use generics internally.

• Use T for reusable type parameters.
• Use generic classes for reusable data structures.
• Use generic methods for reusable operations.

8Questions Interviewers May Ask