Friday, November 4, 2011

PHP Looping - For Loops

Loops execute a block of code a specified number of times, or while a specified condition is true.


The for Loop

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

Syntax

for (init; condition; increment)

  {

  code to be executed;

  }

Parameters:

  • init: Mostly used to set a counter (but can be any code to be executed once at the beginning of the loop)
  • condition: Evaluated for each loop iteration. If it evaluates to TRUE, the loop continues. If it evaluates to FALSE, the loop ends.
  • increment: Mostly used to increment a counter (but can be any code to be executed at the end of the loop)

Note: Each of the parameters above can be empty, or have multiple expressions (separated by commas).

Example

The example below defines a loop that starts with i=1. The loop will continue to run as long as i is less than, or equal to 5. i will increase by 1 each time the loop runs:

<html>

<body>



<?php

for ($i=1; $i<=5; $i++)

  {

  echo "The number is " . $i . "<br />";

  }

?>



</body>

</html>

Output:

The number is 1

The number is 2

The number is 3

The number is 4

The number is 5



The foreach Loop

The foreach loop is used to loop through arrays.

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) - so on the next loop iteration, you'll be looking at the next array value.

Example

The following example demonstrates a loop that will print the values of the given array:

<html>

<body>



<?php

$x=array("one","two","three");

foreach ($x as $value)

  {

  echo $value . "<br />";

  }

?>



</body>

</html>

Output:

one

two

three

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