How to Get Type at Runtime in C# - Simple Guide

In C#, you can get the type of an object at runtime using the GetType() method. This method returns a Type object that describes the exact type of the instance it is called on.

Syntax

The GetType() method is called on an instance of any object to get its runtime type. It returns a Type object that contains information about the object's type.

• objectInstance.GetType(): Calls the method on the object instance.
• Type: The return type representing the type information.

csharp

Type typeInfo = objectInstance.GetType();

Example

This example shows how to get the runtime type of different objects and print their names.

csharp

using System;

class Program
{
    static void Main()
    {
        int number = 42;
        string text = "hello";
        DateTime now = DateTime.Now;

        Console.WriteLine(number.GetType()); // System.Int32
        Console.WriteLine(text.GetType());   // System.String
        Console.WriteLine(now.GetType());    // System.DateTime
    }
}

Output

System.Int32
System.String
System.DateTime

Common Pitfalls

One common mistake is trying to use typeof() on an instance, which is incorrect because typeof() requires a type name, not an object. Another pitfall is assuming GetType() returns the compile-time type; it actually returns the runtime type, which can differ if you use inheritance.

csharp

/* Wrong way - causes compile error */
// var typeInfo = typeof(objectInstance); // Error: 'objectInstance' is a variable, not a type

/* Correct way */
var typeInfo = objectInstance.GetType();

Quick Reference

Remember these key points when getting type at runtime in C#:

• Use instance.GetType() to get the runtime type.
• typeof(TypeName) is for compile-time type references.
• GetType() returns a Type object with type details.
• Runtime type can differ from compile-time type due to inheritance.

Key Takeaways

Use the GetType() method on an object instance to get its runtime type.

GetType() returns a Type object describing the exact type of the instance.

typeof() is used with type names, not object instances.

Runtime type may differ from compile-time type when inheritance is involved.

Always call GetType() on the instance, not on the class name.