C# 4 and .NET 4

68 ❘ ChaPTer 3 Objects And types
Each parameter consists of the name of the type of the parameter, and the name by which it can be
referenced in the body of the method. Also, if the method returns a value, a return statement must be used
with the return value to indicate each exit point. For example:
public bool IsSquare(Rectangle rect)
{
return (rect.Height == rect.Width);
}
This code uses one of the .NET base classes, System.Drawing.Rectangle, which represents a rectangle.
If the method doesn’t return anything, you specify a return type of void because you can’t omit the return
type altogether, and if it takes no arguments, you still need to include an empty set of parentheses after the
method name. In this case, including a return statement is optional — the method returns automatically
when the closing curly brace is reached. You should note that a method can contain as many return
statements as required:
public bool IsPositive(int value)
{
if (value < 0)
return false;
return true;
}
Invoking Methods
The following example, MathTest, illustrates the syntax for definition and instantiation of classes, and
definition and invocation of methods. Besides the class that contains the Main() method, it defines a class
named MathTest, which contains a couple of methods and a field.
using System;
namespace Wrox
{
class MainEntryPoint
{
static void Main()
{
// Try calling some static functions.
Console.WriteLine("Pi is " + MathTest.GetPi());
int x = MathTest.GetSquareOf(5);
Console.WriteLine("Square of 5 is " + x);
// Instantiate at MathTest object
MathTest math = new MathTest(); // this is C#'s way of
// instantiating a reference type
}
}
// Call nonstatic methods
math.value = 30;
Console.WriteLine(
"Value field of math variable contains " + math.value);
Console.WriteLine("Square of 30 is " + math.GetSquare());
// Define a class named MathTest on which we will call a method
class MathTest
{
public int value;
public int GetSquare()
{
return value*value;
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