The Type class
Learn to get a Type object with typeof and GetType.
The Type class
The Type class holds runtime information about a type. It is obtained in two main ways: typeof(MyClass) for types known at compile time, obj.GetType() for the runtime type of an instance.
typeof is an operator that takes a type name. GetType is a method called on an object. Both return a Type. From this object you can list methods, properties, fields and constructors; reflection starts here.
typeof vs GetType
typeof(T) works at compile time; T must be a constant type name. obj.GetType() returns the actual runtime type of any object — it is a virtual method.
When a base class reference holds a derived instance, GetType returns the derived type. E.g. for object o = "text";, o.GetType() returns String. typeof(object) always returns Object.
Exercise Print the type name of an integer
Define int x = 42;. Get its type with Type t = x.GetType();. Print t.Name with Console.WriteLine.
Show example solution
Get the type with Type t = x.GetType();. Print the name with Console.WriteLine(t.Name);.
Example solution:
using System;
class Program
{
static void Main()
{
int x = 42;
Type t = x.GetType();
Console.WriteLine(t.Name);
}
}Test yourself
-
What does obj.GetType() return?
- The class name as a string
- The runtime type of the object (Type)
- The object's field names
- The object's memory address
Show answer
The runtime type of the object (Type) — Correct. GetType returns the runtime type of the object as Type.
-
Complete the typeof call
Type t = ____(string);Show answer
Type t = typeof(string); -
Match the expression to its behavior
- typeof(T)
- Compile time
- obj.GetType()
- Runtime
- typeof(int)
- For a primitive
- t.FullName
- Gives the full name