var vs dynamic

1.var

• Type is decided at compile time

• Strongly typed

• Must be initialized at declaration

• IntelliSense & compile-time checking available

Example

var x = 10;        // int
var name = "Ram"; // string

👉 If you assign a wrong type later → compile-time error

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2.dynamic

• Type is decided at runtime

• Not strongly typed

• No compile-time checking

• Errors occur at runtime

Example

dynamic x = 10;
x = "Ram";        // allowed
x.DoSomething(); // runtime error if method not found

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3.Key Differences (Interview Points)

Feature	var	dynamic
Type resolution	Compile time	Runtime
Type safety	Yes	No
IntelliSense	Yes	No
Error checking	Compile time	Runtime
Type change allowed	No	Yes

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4.When to use?

• Use var when type is obvious and you want clean code

• Use dynamic when working with:

  • COM objects

  • Reflection

  • JSON / loosely typed data

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5.Important interview one-liner

var is statically typed, dynamic is dynamically typed.