w3resource

PHP foreach Statement

Description

PHP 4 introduced "foreach" construct, it works only on arrays. The foreach looping is the best way to access each key/value pair from an array.

Syntax:

foreach (array_expr as $value)
{
statement
}

array_expr is an array. In every loop the value of the current element of the array is assigned to $value and the internal array pointer is advanced by one and the process continue to reach the last array element.

foreach (array_expr as $key => $value)

{

statement

}

array_expr is an array. In every loop the current element's key is assigned to $key and the internal array pointer is advanced by one and the process continue to reach the last array element.

Example -1 :

In the following example, we define an array with five elements and later we use foreach to access array element's value.

<?php
$fruits = array ("Orange", "Apple", "Banana",  "Cherry", " Mango");
foreach ( $fruits as $value )
{
echo  "$value<br />";
} 
?>

Output: 

Orange
Apple
Banana
Cherry
Mango

View the example in the browser

Example -2:

In the following example, both the keys and values of an array have accessed (see the second syntax of the foreach statement).

<?php
$personal_details=array("name" => "Rajesh Rao", "occupation" => "Engineer", age => 39, "country" => "India");
foreach ( $personal_details as $key => $value )
{
echo "$key=$value<br />";
}
?>

Output:

name=Rajesh Rao
occupation=Engineer
age=39
country=India

View the example in the browser

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PHP: Tips of the Day

Getting all defined constants

To get all defined constants including those created by PHP use the get_defined_constants function:

Example:

<?php
$constants = get_defined_constants();
var_dump($constants); // pretty large list

Output:

array(2250) {
  ["E_ERROR"]=>
  int(1)
  ["E_RECOVERABLE_ERROR"]=>
  int(4096)
  ["E_WARNING"]=>
  .....
  .....
  resource(1) of type (stream)
  ["STDOUT"]=>
  resource(2) of type (stream)
  ["STDERR"]=>
  resource(3) of type (stream)
}

To get only those constants that were defined by your app call the function at the beginning and at the end of your script (normally after the bootstrap process):

<?php
$constants = get_defined_constants();
define("HELLO", "hello");
define("WORLD", "world");
$new_constants = get_defined_constants();
$myconstants = array_diff_assoc($new_constants, $constants);
var_export($myconstants);

Output:

array (
  'HELLO' => 'hello',
  'WORLD' => 'world',
)

It's sometimes useful for debugging