I was coding along and suddenly had a duh moment of what’s the difference between ref and out. I knew how they work and I’ve used them sparingly before but I didn’t really have a concrete idea of the difference.
So I looked it up
Out = An additional return value
string doot;
int rawr;
rawr = SomeFooMethod(out doot);
Note: This is not to be abused as stated in the MSDN article “As a matter of good programming style if you find yourself writing a method with many out parameters then you should think about refactoring your code. One possible solution is to package all the return values into a single struct.” — Mental note applied!
Ref = Considered initially assigned by the callee
The MSDN has a much better example than I do….
class RefExample
{
static object FindNext(object value, object[] data, ref int index)
{
// NOTE: index can be used here because it is a ref parameter
while (index < data.Length)
{
if (data[index].Equals(value))
{
return data[index];
}
index += 1;
}
return null;
}
static void Main()
{
object[] data = new object[] {1,2,3,4,2,3,4,5,3};
int index = 0;
// NOTE: must assign to index before passing it as a ref parameter
while (FindNext(3, data, ref index) != null)
{
// NOTE: that FindNext may have modified the value of index
System.Console.WriteLine("Found at index {0}", index);
index += 1;
}
System.Console.WriteLine("Done Find");
}
}
So there you have it. The difference between ref and out
- Jeremy
