(New to C# here) What is the best way to return false in a function if it cannot be executed successfully?

Question

In Javascript or PHP you can have a function that could return, for example, a string in case of success and false in case of failure.
I've noticed (in the few days I've been learning C#) that you need to define a type of value that the function will return, so you need to return that type of value but in case of failure you can't return false.
What is the best way to achieve this behavior and is there an example I can see?
Thank you in advance,
Juan

Answer 1

Juan, be aware that returning null won't work with value types, such as an int, which can't be null. You'd have to use a nullable value type. A nullable int would be declared with a "?", such as:
int? someOtherFunction(int param)
if(something goes great)
return param * 42;
return null;
And you have to use it like this:
int? result = someOtherFunction(666);
if (result != null) // you can also use result.HasValue
// it worked, do something with the result
// if you're doing math with the result, no problem
int x = result * 2;
// but if you're assigning it to another an int, you need to use this syntax
int y = result.Value;
Before nullable value types came along, for a method that returned an int, I'd use a value of something that wouldn't normally be returned by that method to indicate failure, such as a -1.
~~Bonnie DeWitt [C# MVP]
That's something very very important to keep in mind. Can save you from a lot of headaches!
So if you have an int function and it might return NULL, if you are doing Math with the return value you can use it directly, but if you're assigning it to another variable you have to use .Value?
Thanks