Return multiple values to a method caller

Question

I read the C++ version of this question but didn\'t really understand it.

Can someone please explain clearly if it can be done and how?

Answer 1

Previous poster is right. You cannot return multiple values from a C# method. However, you do have a couple of options:

• Return a structure that contains multiple members
• Return an instance of a class
• Use output parameters (using the out or ref keywords)
• Use a dictionary or key-value pair as output

The pros and cons here are often hard to figure out. If you return a structure, make sure it's small because structs are value type and passed on the stack. If you return an instance of a class, there are some design patterns here that you might want to use to avoid causing problems - members of classes can be modified because C# passes objects by reference (you don't have ByVal like you did in VB).

Finally you can use output parameters but I would limit the use of this to scenarios when you only have a couple (like 3 or less) of parameters - otherwise things get ugly and hard to maintain. Also, the use of output parameters can be an inhibitor to agility because your method signature will have to change every time you need to add something to the return value whereas returning a struct or class instance you can add members without modifying the method signature.

From an architectural standpoint I would recommend against using key-value pairs or dictionaries. I find this style of coding requires "secret knowledge" in code that consumes the method. It must know ahead of time what the keys are going to be and what the values mean and if the developer working on the internal implementation changes the way the dictionary or KVP is created, it could easily create a failure cascade throughout the entire application.