Pass by Value in C#

c# pass-by-value
ViV picture ViV · Jun 21, 2012 · Viewed 35.3k times · Source

How can I pass an object of a "MyClass" (C#) by Parameter-by-Value to a method? example:

MyClass obj = new MyClass();
MyClass.DontModify(obj); //Only use it!
Console.Writeline(obj.SomeIntProperty);

...

public static void DontModify(MyClass a)
{
    a.SomeIntProperty+= 100;// Do something more meaningful here
    return;
}

Answer

Daniel Peñalba picture Daniel Peñalba · Jun 21, 2012

By default object types are passed by value in C#. But when you pass a object reference to a method, modifications in the object are persisted. If you want your object to be inmutable, you need to clone it.

In oder to do it, implement the ICloneable interface in your class. Here is a mock example of how to use ICloneable:

public class MyClass : ICloneable
{
  private int myValue;

  public MyClass(int val)
  {
     myValue = val;
  }

  public void object Clone()
  {
     return new MyClass(myValue);
  }
}

Related questions

Passing Objects By Reference or Value in C#

In C#, I have always thought that non-primitive variables were passed by reference and primitive values passed by value. So when passing to a method any non-primitive object, anything done to the object in the method would effect the object …

Read More
Does C# pass a List<T> to a method by reference or as a copy?

Taking my first steps in C# world from C/C++, so a bit hazy in details. Classes, as far as I understood, are passed by reference by default, but what about eg. List<string> like in: void DoStuff(…

Read More
What is the use of "ref" for reference-type variables in C#?

I understand that if I pass a value-type (int, struct, etc.) as a parameter (without the ref keyword), a copy of that variable is passed to the method, but if I use the ref keyword a reference to that variable …

Read More