in_array PHP Explained: How to Check Values in Arrays Like a Pro

in_array PHP – Complete Guide with Examples and Outputs

The in_array PHP function is used to check if a given value exists in an array. It is one of the most commonly used array functions in PHP and works with both indexed and associative arrays.

Syntax of in_array PHP

in_array(mixed $needle, array $haystack, bool $strict = false): bool

• $needle – The value to search for.
• $haystack – The array to search in.
• $strict – If true, the function also checks the type of the value.

Example 1: Basic Indexed Array

<?php
$fruits = ["Apple", "Banana", "Mango"];
if (in_array("Banana", $fruits)) {
    echo "Banana is in the list.";
} else {
    echo "Banana is not in the list.";
}
?>

Output: Banana is in the list.

Example 2: Associative Array

<?php
$person = [
    "name" => "John",
    "age" => 25,
    "city" => "New York"
];
if (in_array("John", $person)) {
    echo "John is found in the array.";
} else {
    echo "John is not found.";
}
?>

Output: John is found in the array.

Example 3: Strict Comparison

<?php
$numbers = [1, "1", 2];
if (in_array(1, $numbers, true)) {
    echo "Strict match for 1 found.";
} else {
    echo "No strict match found.";
}
?>

Output: Strict match for 1 found.

Example 4: Value Not Found

<?php
$colors = ["Red", "Blue", "Green"];
if (in_array("Yellow", $colors)) {
    echo "Yellow is in the array.";
} else {
    echo "Yellow is not in the array.";
}
?>

Output: Yellow is not in the array.

Example 5: Checking Boolean Values

<?php
$values = [true, false, 0, 1];
if (in_array(true, $values, true)) {
    echo "True is found with strict checking.";
} else {
    echo "True is not found.";
}
?>

Output: True is found with strict checking.

Conclusion

The in_array PHP function is simple yet powerful for validating values within arrays. It’s useful for form validations, condition checks, and data filtering. Remember to use the $strict parameter when you want to ensure both value and type match.