Guide to PHP and MySQL (University at Buffalo Version)

Chapter 5: Using PHP Loops

PHP provides a few different control structures that allow you to loop through data using a set of statements.

The PHP `for` Loop

The for statement provides a way to loop through a statement, or group of statements, a number of times.

<?php
for ($i = 0; $i 5; $i++) {
print("\$i = $i<br/>\n");
}
?>

Figure 5-1: A PHP for Loop

$i = 0
$i = 1
$i = 2
$i = 3
$i = 4

Figure 5-2: PHP for Loop Output

The PHP `foreach` Loop

The foreach loop statement provides a way to "walk" through an associative array.

<?php
$statesArray = array("AK" => "Alaska", "AL" => "Alabama", "AR" => "Arkansas", "AZ" => "Arizona");
foreach ($statesArray as $state => $stateValue) {
print("Array element $state = $stateValue<br/>\n");
}
?>

Figure 5-3: PHP foreach Loop

Array element AK = Alaska
Array element AL = Alabama
Array element AR = Arkansas
Array element AZ = Arizona

Figure 5-4: PHP foreach Loop Outuput

The PHP `while` Loop

The while loop statement provides a way to to perform a statement or statements based on a condition being true or false.

<?php
$counter = 0;
$maxNum = 3;
/* Loop until $counter is greater than $maxNum */
while ($counter < $maxNum) {
echo("counter = " . $counter++ . " & maxNum = $maxNum<br/>\n");
}
?>

Figure 5-5: PHP while Loop

counter = 0 & maxNum = 3
counter = 1 & maxNum = 3
counter = 2 & maxNum = 3

Figure 5-6: PHP while Loop Output

The PHP `do / while` Loop

The do ... while loop statements provide a way to to perform a statement or statements based on a condition being true or false. A do ... while loop tests the condition at the end of the loop. So, a do ... while loop will always execute at least once.

<?php
$counter = 4;
$maxNum = 3;
/* Loop until $counter is greater than $maxNum */
do {
echo("counter = " . $counter++ . " & maxNum = $maxNum<br/>\n");
} while ($counter < $maxNum);
?>

Figure 5-7: PHP do / while Loop

counter = 4 & maxNum = 3

Figure 5-8: PHP do ... while Loop Output

Let's Get Started with a PHP for Loop Page!
Let's Get Started with a PHP while Loop Page!