Var vs Dynamic vs Object in C#

1Understanding var, dynamic and object

Hi friends, in this article we will learn the difference between var, dynamic and object in C#. All three can store values, but they work differently. Understanding these differences helps us write safer code, avoid runtime errors and choose the right variable type in our applications.

2Think About a Shopping App

Imagine a shopping app storing a product price, product details and a value received from an external service.

For a known price, we can use var and let C# identify its type. For a value that may contain different data types, we can use object. When the type is determined at runtime, dynamic can be useful.

3How These Three Types Differ

1. var – Compile-time type inference

C# identifies the variable type from its assigned value during compilation. After that, its type cannot change.

2. object – Base type of C# types

It can hold values of different types. Value types such as int are boxed when stored and must be unboxed or cast to use as their original type.

3. dynamic – Runtime binding

The compiler skips normal member checking for dynamic operations. C# checks them at runtime, so an invalid operation can cause a runtime error.

4Let's Try It in C#

Here we store the same product price using all three approaches.

using System;

class Program
{
    static void Main()
    {
        // Type inferred as int
        var price = 1500;

        // Stored as object
        object productPrice = 1500;

        // Type checked at runtime
        dynamic dynamicPrice = 1500;

        Console.WriteLine(price.GetType().Name);
        Console.WriteLine(((int)productPrice) + 500);
        Console.WriteLine(dynamicPrice + 500);

        dynamicPrice = "Hello";
        Console.WriteLine(dynamicPrice);
    }
}

5Check the Program Result

The first line shows the inferred type. The next two lines add 500 to the stored price.

Int32
2000
2000
Hello

6Watch the Code Execute

7Quick Revision

Use var when the compiler can infer a clear type. Use object when you need a general-purpose storage type. Use dynamic when runtime binding is genuinely required.

• var gives compile-time type safety.
• object often needs casting to access members.
• dynamic moves member checking to runtime.

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