What is Dynamic Typing

In C#, dynamic is a special type that tells the compiler:
👉 “Don’t check this variable’s type at compile time. Figure it out at runtime.”

🔹 Example

dynamic value = 10; 
Console.WriteLine(value.GetType()); // System.Int32
 
value = "Hello";   
Console.WriteLine(value.GetType()); // System.String  
 
value = DateTime.Now;   
Console.WriteLine(value.GetType()); // System.DateTime

• Here, value can hold different types over time.

• Unlike var (fixed at compile-time), dynamic is flexible but unsafe.

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🔹 Key Features

1. No compile-time type checking

   dynamic obj = "hello"; obj.NonExistentMethod(); // ❌ No error at compile time // Runtime error: method doesn’t exist

2. Can call members that don’t exist (until runtime)
   Useful when working with:

   • Reflection

   • COM objects

   • JSON / dynamic APIs

   • Interop with dynamic languages (Python, JavaScript)

3. Converts to any type at runtime

   dynamic num = 5; int result = num + 10; // Works

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🔹 var vs dynamic vs object

Keyword	Type Resolution	Checked at	Reassign to other types?
var	Compile-time	Compile-time	❌ (fixed type)
dynamic	Runtime	Runtime	✅ (can change type)
object	Compile-time	Compile-time	✅ but needs casting

Example:

var a = "text"; // string, fixed dynamic b = "text"; // dynamic, can change object c = "text"; // object, needs casting to use members

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🔹 When to Use dynamic

✅ Good for:

• Working with data of unknown type (e.g., parsing JSON).

• Interop with dynamic languages / COM.

• Quick prototyping.

❌ Avoid for:

• Core logic where type safety matters → because errors will only appear at runtime.