Output parametersLike reference parameters, output parameters don't create a new storage location, but use the storage location of the variable specified on the invocation. Output parameters need the out modifier as part of both the declaration and the invocation - that means it's always clear when you're passing something as an output parameter.
Output parameters are very similar to reference parameters
Example :
void Foo (out int x)
{
// Can't read x here - it's considered unassigned
// Assignment - this must happen before the method can complete normally
x = 10;
// The value of x can now be read:
int a = x;
}

// Declare a variable but don't assign a value to it
int y;

// Pass it in as an output parameter, even though its value is unassigned
Foo (out y);
// It's now assigned a value, so we can write it out:
Console.WriteLine (y);
Output:
10