PHP LOOPS

Often when you write code, you want the same block of code to run over and over again a certain number of times. So, instead of adding several almost equal code-lines in a script, we can use loops.

Loops are used to execute the same block of code again and again, as long as a certain condition is true.

In PHP, we have the following loop types:

• while - loops through a block of code as long as the specified condition is true
• do...while - loops through a block of code once, and then repeats the loop as long as the specified condition is true
• for - loops through a block of code a specified number of times
• foreach - loops through a block of code for each element in an array

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1. for Loop

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

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

Syntax

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

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Examples

The example below displays the numbers from 0 to 10:

Code:

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

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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

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2. PHP while Loop

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

Syntax

Example

The example below displays the numbers from 1 to 5:

Code:

<?php
$x = 1;
while($x <= 5) {
  echo "The number is: $x <br>";
  $x++;
}
?>

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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

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3. PHP do...while Loop

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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:

Example

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:

Code:

<?php
$x = 1;
do {
  echo "The number is: $x <br>";
  $x++;
} while ($x <= 5);
?>

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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.

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5. PHP foreach Loop

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

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

Syntax

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.

Example

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

Code

<?php
$colors = array("red", "green", "blue", "yellow");
foreach ($colors as $value) {
  echo "$value <br>";
}
?>

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5. PHP Break

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It was used to "jump out" of a switch statement.It is also useful for immediately stopping a loop

The break statement can also be used to jump out of a loop.

Example

This example jumps out of the loop when x is equal to 4:

code:

<?php
for ($x = 0; $x < 10; $x++) {
  if ($x == 4) {
    break;
  }
  echo "The number is: $x <br>";
}
?>

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6. PHP Continue

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The continue statement breaks one iteration (in the loop), if a specified condition occurs, and continues with the next iteration in the loop.

Example

This example skips the value of 4:

Code:

<?php
for ($x = 0; $x < 10; $x++) {
  if ($x == 4) {
    continue;
  }
  echo "The number is: $x <br>";
}
?>