PHP provides many built-in array functions to count elements, add or remove values, search arrays, sort data, and combine arrays. These functions make array operations easier and reduce the amount of code we need to write.
The count() function returns the number
of elements at the top level of an array.
sizeof() is an alias of
count().
<?php
$fruits = ["Apple", "Mango", "Banana", "Orange"];
echo count($fruits);
echo "<br>";
echo sizeof($fruits);
?>4
4Example with a loop:
<?php
$numbers = [10, 20, 30, 40, 50];
for ($i = 0; $i < count($numbers); $i++) {
echo $numbers[$i] . "<br>";
}
?>10
20
30
40
50
For nested arrays, count() counts only
the outer elements by default. You can use
COUNT_RECURSIVE to count nested elements
as well.
array_push() adds one or more elements
to the end of an array. array_pop()
removes and returns the last element.
<?php
$fruits = ["Apple", "Mango"];
array_push($fruits, "Banana", "Orange");
print_r($fruits);
?>Array
(
[0] => Apple
[1] => Mango
[2] => Banana
[3] => Orange
)Using array_pop():
<?php
$fruits = ["Apple", "Mango", "Banana"];
$removed = array_pop($fruits);
echo "Removed: " . $removed . "<br>";
print_r($fruits);
?>Removed: Banana
Array
(
[0] => Apple
[1] => Mango
)
You can also append one value using
$fruits[] = "Orange";.
array_unshift() adds elements to the
beginning of an array. array_shift()
removes and returns the first element.
Using array_unshift():
<?php
$numbers = [20, 30, 40];
array_unshift($numbers, 10);
print_r($numbers);
?>Array
(
[0] => 10
[1] => 20
[2] => 30
[3] => 40
)Using array_shift():
<?php
$numbers = [10, 20, 30, 40];
$removed = array_shift($numbers);
echo "Removed: " . $removed . "<br>";
print_r($numbers);
?>Removed: 10
Array
(
[0] => 20
[1] => 30
[2] => 40
)These functions reindex the remaining numeric keys in a normal indexed array. String keys are preserved.
array_merge() combines arrays.
Numeric keys are renumbered, while string keys from
later arrays replace matching string keys from
earlier arrays.
<?php
$a = ["Apple", "Mango"];
$b = ["Banana", "Orange"];
$result = array_merge($a, $b);
print_r($result);
?>Array
(
[0] => Apple
[1] => Mango
[2] => Banana
[3] => Orange
)Using array_combine():
array_combine() creates an associative
array from one array of keys and another array of
corresponding values. Both arrays must have the
same number of elements.
<?php
$keys = ["name", "age", "course"];
$values = ["Rahul", 20, "PHP"];
$result = array_combine($keys, $values);
print_r($result);
?>Array
(
[name] => Rahul
[age] => 20
[course] => PHP
)These functions help you retrieve keys and values and check whether a particular key exists.
<?php
$student = [
"name" => "Rahul",
"age" => 20,
"course" => "PHP"
];
print_r(array_keys($student));
echo "<br>";
print_r(array_values($student));
?>Array
(
[0] => name
[1] => age
[2] => course
)
Array
(
[0] => Rahul
[1] => 20
[2] => PHP
)Check whether a key exists:
<?php
$student = [
"name" => "Rahul",
"age" => 20
];
if (array_key_exists("age", $student)) {
echo "Age key exists";
} else {
echo "Age key does not exist";
}
?>Age key exists
Unlike isset(),
array_key_exists() returns true when
the key exists even if its value is null.
in_array() checks whether a value exists
in an array. array_search() returns the
matching key or false if no match is found.
Using in_array():
<?php
$fruits = ["Apple", "Mango", "Banana"];
if (in_array("Mango", $fruits, true)) {
echo "Mango found";
} else {
echo "Mango not found";
}
?>Mango foundUsing array_search():
<?php
$fruits = ["Apple", "Mango", "Banana"];
$key = array_search("Mango", $fruits, true);
if ($key !== false) {
echo "Mango found at index " . $key;
} else {
echo "Mango not found";
}
?>Mango found at index 1
Use !== false when checking
array_search(), because a match may
be found at numeric key 0.
PHP provides sorting functions for ascending and descending order. Some preserve array keys, while others reindex numeric keys.
| Function | Purpose |
|---|---|
sort() |
Ascending order; reindexes numeric keys. |
rsort() |
Descending order; reindexes numeric keys. |
asort() |
Ascending order by value; preserves keys. |
arsort() |
Descending order by value; preserves keys. |
Example: sort()
<?php
$numbers = [40, 10, 30, 20];
sort($numbers);
print_r($numbers);
?>Array
(
[0] => 10
[1] => 20
[2] => 30
[3] => 40
)Example: asort()
<?php
$marks = [
"Rahul" => 80,
"Amit" => 95,
"Priya" => 85
];
asort($marks);
print_r($marks);
?>Array
(
[Rahul] => 80
[Priya] => 85
[Amit] => 95
)
The student names remain associated with their
original marks because asort()
preserves the keys.
array_reverse() – Reverse an array
<?php
$numbers = [10, 20, 30, 40];
print_r(array_reverse($numbers));
?>Array
(
[0] => 40
[1] => 30
[2] => 20
[3] => 10
)array_unique() – Remove duplicate values
<?php
$numbers = [10, 20, 10, 30, 20];
print_r(array_unique($numbers));
?>Array
(
[0] => 10
[1] => 20
[3] => 30
)
The original keys are preserved by
array_unique().
array_slice() – Extract part of an array
<?php
$numbers = [10, 20, 30, 40, 50];
print_r(array_slice($numbers, 1, 3));
?>Array
(
[0] => 20
[1] => 30
[2] => 40
)
By default, array_slice() reindexes
numeric keys in the returned result. It does not
modify the original array.
The following example uses array functions to calculate student totals and averages.
<?php
$students = [
"Rahul" => [80, 85, 90],
"Amit" => [75, 88, 92],
"Priya" => [90, 95, 89]
];
foreach ($students as $name => $marks) {
$total = array_sum($marks);
$subjects = count($marks);
$average = $subjects > 0 ? $total / $subjects : 0;
echo "Student: " . $name . "<br>";
echo "Total: " . $total . "<br>";
echo "Average: " . number_format($average, 2) . "<br>";
echo "<hr>";
}
?>Student: Rahul
Total: 255
Average: 85.00
Student: Amit
Total: 255
Average: 85.00
Student: Priya
Total: 274
Average: 91.33
This example combines array_sum(),
count(), and number_format()
to generate a simple student report.
1. Which function adds elements to the end of an array?
2. Which function sorts an associative array by value while preserving keys?
3. Which function returns the keys of an array?