This post covers the Array Functions section of the Arrays chapter when studying for the Zend PHP 7 Certification.
A list of some of the common functions used when dealing with arrays can be seen below.
array_push()
This function pushes one or more elements onto the end of array.
<?php
$stack = array("orange", "banana");
array_push($stack, "apple", "raspberry");
print_r($stack);
// Outputs:
Array
(
[0] => orange
[1] => banana
[2] => apple
[3] => raspberry
)array_unshift()
This function prepends one or more elements to the beginning of an array.
<?php
$queue = array("orange", "banana");
array_unshift($queue, "apple", "raspberry");
print_r($queue);
// Outputs:
Array
(
[0] => apple
[1] => raspberry
[2] => orange
[3] => banana
)array_pop()
This function pops an element off the end of the array.
<?php
$stack = array("orange", "banana", "apple", "raspberry");
$fruit = array_pop($stack);
print_r($stack);
// Outputs:
Array
(
[0] => orange
[1] => banana
[2] => apple
)array_shift()
This function shifts an element off the beginning of array.
<?php
$stack = array("orange", "banana", "apple", "raspberry");
$fruit = array_shift($stack);
print_r($stack);
// Outputs:
Array
(
[0] => banana
[1] => apple
[2] => raspberry
)array_reverse()
This function returns an array with elements in reverse order. The second parameter passed in is a boolean that if true, preserves the array keys.
<?php
$input = array("php", 4.0, array("green", "red"));
$reversed = array_reverse($input);
$preserved = array_reverse($input, true);
print_r($input);
print_r($reversed);
print_r($preserved);
// Outputs:
Array
(
[0] => php
[1] => 4
[2] => Array
(
[0] => green
[1] => red
)
)
Array
(
[0] => Array
(
[0] => green
[1] => red
)
[1] => 4
[2] => php
)
Array
(
[2] => Array
(
[0] => green
[1] => red
)
[1] => 4
[0] => php
)array_merge()
This function merges one or more arrays. If the input arrays have the same string keys, then the later value for that key will overwrite the previous one.
<?php
$array1 = array("color" => "red", 2, 4);
$array2 = array("a", "b", "color" => "green", "shape" => "trapezoid", 4);
$result = array_merge($array1, $array2);
print_r($result);
// Outputs:
Array
(
[color] => green
[0] => 2
[1] => 4
[2] => a
[3] => b
[shape] => trapezoid
[4] => 4
)array_diff()
This function compares array1 against one or more other arrays and returns the values in array1 that are not present in any of the other arrays.
<?php
$array1 = array("a" => "green", "red", "blue", "red");
$array2 = array("b" => "green", "yellow", "red");
$result = array_diff($array1, $array2);
print_r($result);
// Outputs:
Array
(
[1] => blue
)array_diff_assoc()
Compares array1 against array2 and returns the difference. Unlike array_diff() the array keys are also used in the comparison. Like array_diff(), it returns the values in array1 that are not present in any of the other arrays.
<?php
$array1 = array("a" => "green", "b" => "brown", "c" => "blue", "red");
$array2 = array("a" => "green", "yellow", "red");
$result = array_diff_assoc($array1, $array2);
print_r($result);
// Outputs:
Array
(
[b] => brown
=> blue
[0] => red
)array_diff_key()
Compares the keys from array1 against the keys from array2 and returns the difference. This function is like array_diff() except the comparison is done on the keys instead of the values.
<?php
$array1 = array('blue' => 1, 'red' => 2, 'green' => 3, 'purple' => 4);
$array2 = array('green' => 5, 'blue' => 6, 'yellow' => 7, 'cyan' => 8);
var_dump(array_diff_key($array1, $array2));
// Outputs:
array(2) {
["red"]=>
int(2)
["purple"]=>
int(4)
}sort()
This function sorts elements within an array. The first parameter is the input array, and the second parameter is a sorting flag. Some of the flags that can be used are:
<?php
$fruits = array("lemon", "orange", "banana", "apple");
sort($fruits);
foreach ($fruits as $key => $val) {
echo "fruits[" . $key . "] = " . $val . "\n";
}
// Outputs:
fruits[0] = apple
fruits[1] = banana
fruits[2] = lemon
fruits[3] = orangersort()
This function sorts the array in reverse order.
<?php
$fruits = array("lemon", "orange", "banana", "apple");
rsort($fruits);
foreach ($fruits as $key => $val) {
echo "$key = $val\n";
}
// Outputs:
0 = orange
1 = lemon
2 = banana
3 = appleasort()
This function sorts an array and maintains index association.
<?php
$fruits = array("d" => "lemon", "a" => "orange", "b" => "banana", "c" => "apple");
asort($fruits);
foreach ($fruits as $key => $val) {
echo "$key = $val\n";
}
// Outputs:
c = apple
b = banana
d = lemon
a = orangeThe fruits have been sorted in alphabetical order, and the index associated with each element has been maintained.
ksort()
This function sorts an array by key.
<?php
$fruits = array("d"=>"lemon", "a"=>"orange", "b"=>"banana", "c"=>"apple");
ksort($fruits);
foreach ($fruits as $key => $val) {
echo "$key = $val\n";
}
// Outputs:
a = orange
b = banana
c = apple
d = lemonusort()
This function sorts an array using a user defined comparison function.
<?php
function cmp($a, $b)
{
if ($a == $b) {
return 0;
}
return ($a < $b) ? -1 : 1;
}
$a = array(3, 2, 5, 6, 1);
usort($a, "cmp");
foreach ($a as $key => $value) {
echo "$key: $value\n";
}
// Outputs:
0: 1
1: 2
2: 3
3: 5
4: 6natsort()
This function sorts an array using a “natural order” algorithm.
<?php
$array1 = $array2 = array("img12.png", "img10.png", "img2.png", "img1.png");
asort($array1);
print_r($array1);
natsort($array2);
print_r($array2);
// Outputs:
Array
(
[3] => img1.png
[1] => img10.png
[0] => img12.png
[2] => img2.png
)
Array
(
[3] => img1.png
[2] => img2.png
[1] => img10.png
[0] => img12.png
)View the other sections:
Note: This article is based on PHP version 7.0.