Using Arrays in PHP

raj · #11 08-16-2007, 01:36 AM

hi all,

Can any one give details about ArrayIterator? Explain the usage of this function.

Sabari · #12 08-16-2007, 02:42 AM

ArrayIterator is the Component of SPL, here explained detailed about SPL and Iterators...

what is Standard PHP Library (SPL)?
SPL provides a standard set of interfaces for PHP5. The aim of SPL is to implement some efficient data access interfaces and classes for PHP. Functionally it is designed to traverse aggregate structures (anything you want to loop over). These may include arrays, database result sets, xml trees, directory listings or any list at all. Currently SPL deals with Iterators. To see all the classes available to SPL, this simple snippet will show you.

<?php
// a simple foreach() to traverse the SPL class names

foreach(spl_classes() as $key=>$value)
{
echo $key.' -> '.$value.'<br />';
}
?>

What are iterators?

An Iterator is an object that traverses a structure eg: an array or a directory listing or possibly a set of database result sets or other resource. This is not an accurate discription, but more will become clear later by way of example. There are different types of iterators for dealing with different types of data such as array Iterators, Directory Iterators and more. Here we will begin to get familiar with them beginning with the DirectoryIterator. What is important to note is they can all be accessed with a standard interface. This means that regardless of the data type, access to the information is standardised. This is a real step forward for PHP.

ArrayIterator

The ArrayIterator makes use of the ArrayObject to traverse arrays and an understanding of this is important. Much like the Directory iterator, we can see the methods available to the Array Iterator with a simple snippet.

<?php
foreach(get_class_methods(new ArrayIterator()) as $key=>$method)
{
echo $key.' -> '.$method.'<br />';
}
?>

Sabari · #13 08-16-2007, 03:02 AM

here we can discuss briefly one by one about ArrayIterator...

ArrayIterator::current

ArrayIterator::current -- Return current array entry
Description
mixed ArrayIterator::current ( void )

This function returns the current array entry

Example: ArrayIterator::current()
<?php
$array = array('1' => 'one',
'2' => 'two',
'3' => 'three');

$arrayobject = new ArrayObject($array);

for($iterator = $arrayobject->getIterator();
$iterator->valid();
$iterator->next()) {

echo $iterator->key() . ' => ' . $iterator->current() . "\n";
}
?>

The above example will output:
1 => one
2 => two
3 => three

raj · #14 08-16-2007, 10:11 PM

hi all,

- Create array containing variables and their values.

- This function create a array & this array key from variables name & values from their values.

eg:

$city = "San Francisco";
$state = "CA";
$event = "SIGGRAPH";

$location_vars = array("city", "state");

$result = compact("event", $location_vars);

After this, $result will be:

Array
(
[event] => SIGGRAPH
[city] => San Francisco
[state] => CA
)

raj · #15 08-16-2007, 10:37 PM

hi all,

What is difference between array_diff & array_diff_assoc function?

raj · #16 08-16-2007, 10:46 PM

hi all,

array_flip function:

-- Exchanges all keys with their associated values in an array ( Convert all keys to value & their values to key ).

$array = array("a" => 1, "b" => 1, "c" => 2);
$array = array_flip($array);
print_r($array);

Result:
Array
(
[1] => b
[2] => c
)

Sabari · #17 08-16-2007, 10:59 PM

we can discuss briefly one by one about ArrayIterator...
ArrayIterator::key

ArrayIterator::key -- Return current array key
Description
mixed ArrayIterator::key ( void )

This function returns the current array key

ArrayIterator::key() example
<?php
$array = array('key' => 'value');

$arrayobject = new ArrayObject($array);
$iterator = $arrayobject->getIterator();

echo $iterator->key(); //key
?>

Sabari · #18 08-16-2007, 11:00 PM

ArrayIterator::next

ArrayIterator::next -- Move to next entry
Description
void ArrayIterator::next ( void )

This function moves the iterator to the next entry.

ArrayIterator::next() example
<?php
$arrayobject = new ArrayObject();

$arrayobject[] = 'zero';
$arrayobject[] = 'one';

$iterator = $arrayobject->getIterator();

while($iterator->valid()) {
echo $iterator->key() . ' => ' . $iterator->current() . "\n";

$iterator->next();
}
?>

The above example will output:

0 => zero 1 => one

Sabari · #19 08-16-2007, 11:01 PM

ArrayIterator::rewind

ArrayIterator::rewind -- Rewind array back to the start
Description
void ArrayIterator::rewind ( void )

This function rewinds the iterator to the beginning.

ArrayIterator::rewind() example
<?php
$arrayobject = new ArrayObject();

$arrayobject[] = 'zero';
$arrayobject[] = 'one';
$arrayobject[] = 'two';

$iterator = $arrayobject->getIterator();

$iterator->next();
echo $iterator->key(); //1

$iterator->rewind(); //rewinding to the begining
echo $iterator->key(); //0
?>

Sabari · #20 08-16-2007, 11:04 PM

ArrayIterator::seek

ArrayIterator::seek -- Seek to position
Description
void ArrayIterator::seek ( int position )

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