$_GET is an associative array of variables passed in URL.

Example:

http://exemplo.com?name=Alejandro&age=23&gender=male

That URL have many variables:

print_r($_GET);

array
(
	name => Alejandro,
	age => 23,
	gender => male
)

We can access the variable values using indexes:

echo $_GET['age']; // show 23
echo $_GET['gender']; // show male

From array to URL parameters

Doesn’t exists an native PHP function to convert array in URL parameters. So lets make our function:

function arrtourl($arr, $entity=true, $prefix='') {
	$params = array();
	foreach ($arr as $k => $v)
		if ($v)
			$params[] = is_array($v) ? arrtourl($v, $entity, $prefix ? $prefix.'['.$k.']' : $k) : sprintf($prefix ? $prefix.'[%s]' : '%s', urlencode($k)).'='.urlencode($v);
	return implode($entity ? '&' : '&', $params);
}

Parameters

$arr

is the array to be converted.

$entity

is a boolean who defines if the parameters will be joined using & or &. The default value is true because in most cases the URL parameters create from here will be used in HTML content.

$prefix

this parameters are used in recursions when $arr is an matrix.

Examples

Simple:

$arr = array(
	'id' => 968,
	'cat' => 'php'
);

echo arrtourl($arr);

>> id=968&cat=php

Matrix:

$mat = array(
	'test' => array(
		'id' => 968,
		'cat' => php
	),
	'status' => 1,
	'seq' => array(
		1,
		2,
		3
	)
);

echo arrtourl($mat);

>> test[id]=968&test[cat]=php&status=1&seq[0]=1&seq[1]=2&seq[2]=3

Many dimensions:

$arr = array(
	'val' => array(
		array(
			array(
				'test'
			)
		)
	)
);

echo arrtourl($arr);

>> val[0][0][0]=test

Just &:

$arr = array(
	'id' => 968,
	'cat' => 'php',
);

// id=968&cat=php
$url = arrtourl($arr, false);

header('Location: mypage?'.$url);

Adding prefix:

$arr = array(
	'id' => 968,
	'cat' => 'php'
);

echo arrtourl($arr, false, 'post');

>> post[id]=968&post[cat]=php