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PHP Loops
PHP Loops
Usually when you write code, you want the same code block to run repeatedly a certain number of times. So, instead of adding a few lines of code that almost match the text, we can use loops.
Loops are used to use the same block of code many times, as long as the particular situation is true.
In PHP, we have the following loop types:
while- loops through a block of code as long as the specified condition is truedo...while- loops through a block of code once, and then repeats the loop as long as the specified condition is truefor- loops through a block of code a specified number of timesforeach- loops through a block of code for each element in an array
PHP while Loop
While loop - Connects to the code block as long as the specified condition is true.
The PHP while Loop
Loop while using the code block as long as the condition stated is true.
Syntax
while (condition is true) {
code to be executed;
}
Examples
The example below shows the numbers from 1 to 5:
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 100 in tens:
Example
<?php
$x = 0;
while($x <= 100) {
echo "The number is: $x <br>";
$x+=10;
}
?>
Example Explained
- $x = 0; - Initialize the loop counter ($x), and set the start value to 0
- $x <= 100 - Continue the loop as long as $x is less than or equal to 100
- $x+=10; - Increase the loop counter value by 10 for each iteration
PHP do while Loop
Do...while loop - It goes into the code block once, and then repeats the loop as long as the specified condition is true.
The PHP do..while Loop
The do...while the loop will always use the code block once, then check the status, and repeat the loop when the specified state is true.
Syntax
do
{
code to be executed;
}
while (condition is true);
Examples
The example below starts with setting the variable x x 1 ($ x = 1). Then, loop the do while it will record another output, and then raise the variable $ x per 1. Then the condition is checked ($ x less, or equal to 5?), And the loop will continue to work as long as $ x is less, or equal to 5:
Example
<?php
$x = 1;
do {
echo "The number is: $x <br>";
$x++;
} while ($x <= 5);
?>
Note: In practice do... while loop status is checked AFTER using statements within the loop. This means that do... while the loop will use its statements at least once, even if the situation is false. See an example below.
This example sets a variable of x x to 6, then uses a loop, and then the status is checked:
Example
<?php
$x = 6;
do {
echo "The number is: $x <br>";
$x++;
} while ($x <= 5);
?>
PHP for Loop
For Loop - A loop in a code block a certain number of times.
The PHP for Loop
The loop is used if you know in advance how often the script should work.
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 shows 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
- $x++ - Increase the loop counter value by 1 for each iteration
This example counts 100 in tens:
Example
<?php
for ($x = 0; $x <= 100; $x+=10)
{
echo "The number is: $x <br>";
}
?>
Example Explained
- $x = 0; - Initialize the loop counter ($x), and set the start value to 0
- $x <= 100; - Continue the loop as long as $x is less than or equal to 100
- $x+=10 - Increase the loop counter value by 10 for each iteration
PHP foreach Loop
For-loop - Connects to each element code block to the same members.
The PHP foreach Loop
The forloop only applies to the same members, and is used to connect between each key / value pairing in the system.
Syntax
foreach ($array as $value)
{
code to be executed;
}
In each loop of the loop, the current element of the same members is assigned to the value of $ and the identifier of the same members is moved one by one, until it reaches the last half of the same members.
Examples
The following example will give you the colors of the same given members ($ colors):
Example
<?php
$colors = array("red", "green", "blue", "yellow");
foreach ($colors as $value) {
echo "$value <br>";
}
?>
The following example will extract both the keys and the values of the same given member ($ age):
Example
<?php
$age = array("Peter"=>"35", "Ben"=>"37", "Joe"=>"43");
foreach($age as $x => $val) {
echo "$x = $val<br>";
}
?>
PHP Break and Continue
PHP Break
You have already seen the break statement used in the previous chapter of this study. Used for "skipping" on the switch statement.
The break statement can also be used to jump into a loop.
This pattern comes out of the loop when x is equal to 4:
Example
<?php
for ($x = 0; $x < 10; $x++) {
if ($x == 4) {
break;
}
echo "The number is: $x <br>";
}
?>
PHP Continue
The continue statement terminates one replica (loop), if the specified condition occurs, and continues the following repetition in loop.
This example exceeds 4 value:
Example
<?php
for ($x = 0; $x < 10; $x++) {
if ($x == 4) {
continue;
}
echo "The number is: $x <br>";
}
?>
Break and Continue in While Loop
You can also use break and continue while loops:
Break Example
<?php
$x = 0;
while($x < 10) {
if ($x == 4) {
break;
}
echo "The number is: $x <br>";
$x++;
}
?>
Continue Example
<?php
$x = 0;
while($x < 10) {
if ($x == 4) {
$x++;
continue;
}
echo "The number
is: $x <br>";
$x++;
}
?>