PHP Loops

PHP while Loop

The while loop - Loops through a block of code as long as the specified condition is true.

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The PHP while Loop

The while loop executes a block of code as long as the specified condition is true.

Syntax

while (condition is true) {
    code to be executed;
}

Example

<?php
$x = 1;

while($x <= 5) {
    echo "The number is: $x <br>";
    $x++;
}
?>

Example Explained

• $x = 1; - Initialize the loop counter ($x), and set the start value to 1
• $x <= 5 - Continue the loop as long as $x is less than or equal to 5
• $x++; - Increase the loop counter value by 1 for each iteration

This example counts to 100 by tens:

Example

<?php
$x = 0;

while($x <= 100) {
    echo "The number is: $x <br>";
    $x+=10;
}
?>

PHP do while Loop

The do...while loop - Loops through a block of code once, and then repeats the loop as long as the specified condition is true.

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The PHP do...while Loop

The do...while loop will always execute the block of code once, it will then check the condition, and repeat the loop while the specified condition is true.

Syntax

do {
    code to be executed;} while (condition is true);

Examples

The example below first sets a variable $x to 1 ($x = 1). Then, the do while loop will write some output, and then increment the variable $x with 1. Then the condition is checked (is $x less than, or equal to 5?), and the loop will continue to run as long as $x is less than, or equal to 5:

Example

<?php
$x = 1;

do {
    echo "The number is: $x <br>";
    $x++;
} while ($x <= 5);
?>

Note: In a do...while loop the condition is tested AFTER executing the statements within the loop. This means that the do...while loop will execute its statements at least once, even if the condition is false. See example below.

This example sets the $x variable to 6, then it runs the loop, and then the condition is checked:

Example

<?php
$x = 6;

do {
    echo "The number is: $x <br>";
    $x++;
} while ($x <= 5);
?>

PHP for Loop

The for loop - Loops through a block of code a specified number of times.

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The PHP for Loop

The for loop is used when you know in advance how many times the script should run.

Syntax

for (init counter; test counter; increment counter) {
    code to be executed for each iteration;
}

Parameters:

• init counter: Initialize the loop counter value
• test counter: Evaluated for each loop iteration. If it evaluates to TRUE, the loop continues. If it evaluates to FALSE, the loop ends.
• increment counter: Increases the loop counter value

Examples

The example below displays the numbers from 0 to 10:

Example

<?php
for ($x = 0; $x <= 10; $x++) {
    echo "The number is: $x <br>";
}
?>

Example Explained

• $x = 0; - Initialize the loop counter ($x), and set the start value to 0
• $x <= 10; - Continue the loop as long as $x is less than or equal to 10
• $x++ - Increase the loop counter value by 1 for each iteration

This example counts to 100 by tens:

Example

<?php
for ($x = 0; $x <= 100; $x+=10) {
    echo "The number is: $x <br>";
}
?>

PHP foreach Loop

The foreach loop - Loops through a block of code for each element in an array.

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The PHP foreach Loop

The foreach loop works only on arrays, and is used to loop through each key/value pair in an array.

Syntax

foreach ($array as $value) {
  code to be executed;
}

For every loop iteration, the value of the current array element is assigned to $value and the array pointer is moved by one, until it reaches the last array element.

Examples

The following example will output the values of the given array ($colors):

Example

<?php
$colors = array("red", "green", "blue", "yellow");

foreach ($colors as $value) {
  echo "$value <br>";
}
?>

The following example will output both the keys and the values of the given array ($age):

Example

<?php
$age = array("Peter"=>"35", "Ben"=>"37", "Joe"=>"43");

foreach($age as $x => $val) {
  echo "$x = $val<br>";
}
?>