Methods - Illustrated C# 2005 - page 72

Parameters
So far, you have seen that methods are named units of code that can be called from many
places in a program, and can return a single value to the calling code. Returning a single value
is certainly valuable, but what if you need to return multiple values? Also, it would be useful to
be able to pass data into a method when it starts execution. Parameters are special variables
that allow you to do both these things.

Formal Parameters
Formal parameters are local variables that are declared in the method's parameter list, rather
than in the body of the method.
The following method header shows the syntax of parameter declarations. It declares two
formal parameters—one of type int , and the other of type float .

public void PrintSum( int x, float y )
{ ... } ↑
Formal parameter declarations

￿ Because formal parameters are variables, they have a data type and a name, and can be

written to and read from.

￿ Unlike a method's other local variables, the parameters are defined outside the method

body and initialized before the method starts, except in one case, which I will cover
shortly.

￿ The parameter list can have any number of formal parameter declarations, and the dec-

larations must be separated by commas.

The formal parameters are used throughout the method body, for the most part, just like
other local variables. For example, the following declaration of method PrintSum uses two for-
mal parameters, x and y , and a local variable, Sum , all of type int .

public void PrintSum( int x, int y )
{
int Sum = x + y;
Console.WriteLine("Newsflash: {0} + {1} is {2}", x, y, Sum);
}