Page 110 - Beginning PHP 5.3

Part II: Learning the Language
This code displays the first 10 numbers in the Fibonacci sequence. First the XHTML page header and
table header are displayed. Then a for loop generates each Fibonacci number, breaking out into HTML
each time through the loop to display a table row containing the number. Notice how the script flips
between HTML markup and PHP code several times using the < ?php ... ? > tags. The alternating
table rows are achieved with a CSS class in the head element combined with an if decision embedded
within the table row markup.

You can see how easy it is to output entire chunks of HTML — in this case, a table row — from inside a
loop, or as the result of a decision.

Summary
In this chapter you explored two key concepts of PHP (or any programming language for that matter):
decisions and loops. Decisions let you choose to run a block of code based on the value of an expression,
and include:

❑ The if statement for making simple “ either/or ” decisions
❑ The else and elseif statements for decisions with multiple outcomes
❑ The switch statement for running blocks of code based on the value of an expression
❑ The ? (ternary) operator for writing compact if...else style decisions

Loops allow you to run the same block of code many times until a certain condition is met. You
learned about:

❑ while loops that test the condition at the start of the loop
❑ do...while loops that test the condition at the end of the loop

❑ for loops that let you write neat “ counting ” loops
You also looked at other loop - related statements, including the break statement for exiting a loop and the
continue statement for skipping the current loop iteration. Finally, you explored nested loops, and looked
at a powerful feature of PHP: the ability to mix decision and looping statements with HTML markup.

In the next chapter you take a thorough look at strings in PHP, and how to manipulate them. Before
reading it, though, try the following two exercises to cement your understanding of decisions and loops.
As always, you can find solutions to the exercises in Appendix A.

Exercises

1. Write a script that counts from 1 to 10 in steps of 1. For each number, display whether that
number is an odd or even number, and also display a message if the number is a prime number.
Display this information within an HTML table.
2. Modify the homing pigeon simulator to simulate two different pigeons on the same map, both
flying to the same home point. The simulation ends when both pigeons have arrived home.

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