Boxing a Value Type in C# – Basics & Best Practices

What is C# Boxing?

C# boxing is a concept in which a value type variable is converted into an object type. In other words, it is a process of wrapping a value type variable in an object type. The wrapper is called a “box”. This process allows users to store value types in an object type variable and also enables the use of type-safe collections such as generic lists.

Why Use C# Boxing?

C# boxing is useful when developers need to store data of various types in a single collection. For example, a List can only contain objects - not primitive data types such as int and string. By using boxing, developers can store primitive data types in the List. In addition, some methods and properties require objects as parameters, while others require primitive data types. By using boxing, developers can pass both objects and primitive data types as parameters.

How is C# Boxing Performed?

C# boxing is performed with the help of the ‘box’ keyword. It is used to convert a value type into an object type. Consider the following example:

int x = 10;
object obj = x;

In this code, the object obj contains the value 10, which was previously stored in the int variable x. The process of storing the integer value in the object variable is known as boxing.

Performance Impact of C# Boxing

Although boxing is useful in certain scenarios, it has an impact on the performance of an application. Boxing causes unnecessary memory allocations as it requires an extra object to be created when a value type is being stored in an object. This results in extra memory consumption and reduced performance. Therefore, it is important to use boxing judiciously.