Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
765 views
in Technique[技术] by (71.8m points)

c# - cast object with a Type variable

The following doesn't work, of course. Is there a possible way, which is pretty similar like this?

Type newObjectType = typeof(MyClass);

var newObject = givenObject as newObjectType;
See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

newObjectType is an instance of the Type class (containing metadata about the type) not the type itself.

This should work

var newObject = givenObject as MyClass;

OR

var newObject = (MyClass) givenObject;

Casting to an instance of a type really does not make sense since compile time has to know what the variable type should be while instance of a type is a runtime concept.

The only way var can work is that the type of the variable is known at compile-time.


UPDATE

Casting generally is a compile-time concept, i.e. you have to know the type at compile-time.

Type Conversion is a runtime concept.


UPDATE 2

If you need to make a call using a variable of the type and you do not know the type at compile time, you can use reflection: use Invoke method of the MethodInfo on the type instance.

object myString = "Ali";
Type type = myString.GetType();
MethodInfo methodInfo = type.GetMethods().Where(m=>m.Name == "ToUpper").First();
object invoked = methodInfo.Invoke(myString, null);
Console.WriteLine(invoked);
Console.ReadLine();

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...