Build Your Own ASP.NET 2.0 Web Site Using C# & VB, Second Edition

call which will return an integer during execution. Converting numbers to strings

is a very common task in ASP.NET, so it’s good to get a handle on it early.

Converting Numbers to Strings

There are more ways to convert numbers to strings in .NET, as the following

lines of VB code illustrate:

messageLabel.Text = addUp(5, 2).ToString()

messageLabel.Text = Convert.ToString(addUp(5, 2))

If you prefer C#, these lines of code perform the same operations as the VB

code above:

messageLabel.Text = addUp(5, 2).ToString();

messageLabel.Text = Convert.ToString(addUp(5, 2));

Don’t be concerned if you’re a little confused by how these conversions work,

though—the syntax will become clear once we discuss object oriented concepts

later in this chapter.

Operators

Throwing around values with variables and functions isn’t of much use unless

you can use them in some meaningful way, and to do so, we need operators. An

operator is a symbol that has a certain meaning when it’s applied to a value.

Don’t worry—operators are nowhere near as scary as they sound! In fact, in the

last example, where our function added two numbers, we were using an operator:

the addition operator, or + symbol. Most of the other operators are just as well

known, although there are one or two that will probably be new to you. Table 3.2

outlines the operators that you’ll use most often in your ASP.NET development.

Operators Abound!

The list of operators in Table 3.2 is far from complete. You can find detailed

(though poorly written) lists of the differences between VB and C# operators

on the Code Project web site.

3

3

http://www.codeproject.com/dotnet/vbnet_c__difference.asp

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Chapter 3: VB and C# Programming Basics

Table 3.2. Common ASP.NET operators

DescriptionC#VB

greater than>>

greater than or equal to>=>=

less than<<

less than or equal to<=<=

not equal to!=<>

equals===

assigns a value to a variable==

or||OrElse

and&&AndAlso

concatenate strings+&

create object or arraynewNew

multiply**

divide//

add++

subtract--

The following code uses some of these operators:

Visual Basic

If (user = "Zak" AndAlso itemsBought <> 0) Then

messageLabel.Text = "Hello Zak! Do you want to proceed to " & _

"checkout?"

End If

C#

if (user == "Zak" && itemsBought != 0)

{

messageLabel.Text = "Hello Zak! Do you want to proceed to " +

"checkout?";

}

Here, we use the equality, inequality (not equal to), and logical “and” operators

in an If statement to print a tailored message for a given user when he has put

a product in his electronic shopping cart. Of particular note is the C# equality

operator, ==, which is used to compare two values to see if they’re equal. Don’t

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Operators