What are Generics in C# and why are they useful?

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ICSM Computer · Answer

Generics in C# allow you to define classes, interfaces, methods, or delegates with a placeholder for the data type. This means you can write code that works with
any data type while maintaining type safety and avoiding runtime casting.
Why Generics Are Useful:
Benefit
Explanation
Type Safety
Errors are caught at compile time instead of runtime.
Code Reusability
You can write logic once and reuse it with different types.
Performance
Avoids boxing/unboxing with value types.
Clarity
Clear intent — you know what type is being used in advance.
Example: Without Generics
public class Box
{
    public object Item { get; set; }
}
var intBox = new Box();
intBox.Item = 123;
int value = (int)intBox.Item; // Requires casting
Problems:
No compile-time type check.Requires casting → possible runtime exceptions.
With Generics:
public class Boxandlt;Tandgt;
{
    public T Item { get; set; }
}
var intBox = new Boxandlt;intandgt;();
intBox.Item = 123;
int value = intBox.Item; // No casting, type-safe
Generic Method Example:
public T GetFirstandlt;Tandgt;(Listandlt;Tandgt; items)
{
    return items.First();
}
Can be called as:
int first = GetFirst(new Listandlt;intandgt; { 1, 2, 3 });
string firstStr = GetFirst(new Listandlt;stringandgt; { "a", "b" });
.NET Built-in Examples:
Listandlt;Tandgt;Dictionaryandlt;TKey, TValueandgt;Taskandlt;Tandgt;Nullableandlt;Tandgt; (i.e., int?)
Summary:
Generics allow you to write:
Flexible, yet strongly typed codeWithout duplicating logic for different typesAnd with better performance and safety
Let me know if you want to see:
Generic constraints (where T : class, etc.)Generic interfacesComparisons with templates in C++

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What are Generics in C# and why are they useful?

Anubhav Kumar

Can you answer this question?

1 Answers

Why Generics Are Useful:

Example: Without Generics

With Generics:

Generic Method Example:

.NET Built-in Examples:

Summary:

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Benefit	Explanation
Type Safety	Errors are caught at compile time instead of runtime.
Code Reusability	You can write logic once and reuse it with different types.
Performance	Avoids boxing/unboxing with value types.
Clarity	Clear intent — you know what type is being used in advance.