Page 95 - Beginning PHP 5.3
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Chapter 4: Decisions and Loops
The ternary operator can be thought of as a compact version of the if...else construct. The preceding
code reads as follows: If expression1 evaluates to true , the overall expression equals expression2 ;
otherwise, the overall expression equals expression3 .
Here ’ s a “ real world ” example to make this concept clearer:
$widgets = 23;
$plenty = “We have plenty of widgets in stock.”;
$few = “Less than 10 widgets left. Time to order some more!”;
echo ( $widgets > = 10 ) ? $plenty : $few;
This code is functionally equivalent to the example in the else statement section earlier in this chapter.
Here ’ s how it works.
Three variables are created: the $widgets variable, with a value of 23 , and two variables, $plenty and
$few , to hold text strings to display to the user. Finally, the ternary operator is used to display the
appropriate message. The expression $widgets > = 10 is tested; if it ’ s true (as it will be in this case),
the overall expression evaluates to the value of $plenty . If the test expression happens to be false , the
overall expression will take on the value of $few instead. Finally, the overall expression — the result of
the ternary operator — is displayed to the user using echo() .
Code that uses the ternary operator can be hard to read, especially if you ’ re not used to seeing the
operator. However, it ’ s a great way to write compact code if you just need to make a simple if...else
type of decision.
Try It Out Use Decisions to Display a Greeting
Here’s a simple example that demonstrates the if, elseif, and else statements, as well as the ?
(ternary) operator. Save the script as greeting.php in your document root folder.
This script (and most of the other scripts in this book) link to the common.css style sheet file listed in
Chapter 2, so make sure you have common.css in your document root folder too.
<!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.0 Strict//EN”
“http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd”>
<html xmlns=”http://www.w3.org/1999/xhtml” xml:lang=”en” lang=”en”>
<head>
<title>Greetings</title>
<link rel=”stylesheet” type=”text/css” href=”common.css” />
</head>
<body>
<?php
$hour = date( “G” );
$year = date( “Y” );
if ( $hour >= 5 && $hour < 12 ) {
echo “<h1>Good morning!</h1>”;
} elseif ( $hour >= 12 && $hour < 18 ) {
echo “<h1>Good afternoon!</h1>”;
} elseif ( $hour >= 18 && $hour < 22 ) {
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