Beginning C# 3.0

7.1. Program Loops

If you're sitting in a public building right now, look at the ceiling. Chances are you can see sprinklers embedded there. In most modern office buildings, each room has one or more sprinklers in it. Modern sprinklers are monitored by software that tests each one to see if it senses a fire. If a building has 500 sprinklers, the program samples the current state of sprinkler one and, assuming everything's okay, goes on to test sprinkler two. This process continues until sprinkler 500 is tested. Assuming all 500 passed the test and no fire is sensed, the program goes back to the start and tests sprinkler one again. The program then moves on to sprinkler two and the entire process repeats itself. It's fairly quick, probably taking less than a few seconds to test all 500 sprinklers.

The process of repeated testing is performed by a program loop within the fire system software. If one of the sprinkler system tests failed, the software would likely branch out of the loop and process code that would sound the alarm, make sure there is water pressure to feed the sprinkler system, and place a call to the fire department. Loops are everywhere around us, in everything from fire alarms to elevators to circuits in your car's engine and safety equipment. Indeed, people who find their lives boring are perhaps caught in endless loops wherein they do the same things over and over again!

7.1.1. Good Loops, Bad Loops

Not all loops are created equal. As you will see in a moment, ...