Stephens' C# Programming with Visual Studio® 2010 24-Hour Trainer

Repeating Program Steps

One of the computer’s greatest strengths is its ability to perform the exact same calculation

again and again without getting bored or making careless mistakes. It can calculate the average

test scores for a dozen students, print a hundred advertisements, or compute the monthly bills

for a million customers with no trouble or complaining.

The lessons you’ve read so far, however, don’t tell you how to do these things. So far every step

the computer takes requires a separate line of code. To add up 10 numbers, you would need to

write 10 lines of code.

In this lesson you learn how to make the computer execute the same lines of code many

times. You learn how to loop through arrays and collections of items to take action or per-

form calculations on them.

The following sections describe the kinds of loops provided by C#. The final section describes

two statements you can use to change the way a loop works:

break and continue.

FOR LOOPS

A for loop uses a variable to control the number of times it executes a series of statements.

The

for loop’s syntax is as follows:

for (initialization; doneTest; next)

{

statements...

}

Where:

initialization



— This statement gets the loop ready to start. Often this part declares

and initializes the looping variable.

doneTest



— This is a Boolean expression that determines when the loop stops. The

loop continues running as long as this expression ...