Return an Object or Return a Value

Question

Hi What is the difference in returning an Object and returning a Value please. Thanks Steven

Vulpes · Answer

If a method returns an object then it returns a reference to the object (i.e. its address on the heap) not the object itself. In contrast if a method returns a value then it returns the actual value not an address.

Vulpes · Answer

It looks like the GetCustomersWithOrderStatistics method is returning some sort of Customer collection which will almost certainly be a reference type. So the method is therefore returning an object reference rather than a value. The basic difference between a variable of a reference type and a variable of a value type is that the former holds an object reference (i.e. a pointer) and the latter holds the actual value itself. However confusing terminology abounds in programming and you'll often see what is being assigned to a variable referred to as a 'value' even though it is in fact an object reference! The designers of C# haven't helped by using the name 'value' for the implicit parameter used in a property 'set' regardless of whether the property type is a reference type or a value type - though I suppose it might have been even more confusing if they'd used different names for each type :)

S · Answer

Vulpes Given the below example which you kindly commented on in another thread of mine. Would the Return Value be the Object Reference that will be stored? // Otherwise invoke the GetCustomersWithOrderStatistics method and store the return value in the customers local variable instead. customers = _customerDao.GetCustomersWithOrderStatistics(sort); Thanks Steven

Senthilkumar · Answer

Hi Lets see from the basics. object obj = 10; //Derived from the System.Object type When the object is created it will be stored in the heap memory. It is object type and it will have the memory address of heap and when you pass to the other method it passes the actual address not the actual value. When you change in one location in the current context throughout the reference will be changed. int i = 5; //Derived from the System.ValueType; The value type will be stored in the stack and it will have the value in the actual memory location. When you pass to a method it will pass the actual value. For example object obj = 10; Swap(obj); public void Swap(object obj1) { obj1 = 20; } When you pass the object it will send the actual address and when you reassign the object value in the method it will change the value in the declaration variable of obj. The object delegate string are the example of object type (reference type) The int float enum struct are the example of value type (stack) I hope you this will help you to understand.