The SplFixedArray class

The SplFixedArray class

Introduction

(PHP 5 >= 5.3.0, PHP 7, PHP 8)

The SplFixedArray class provides the main functionalities of array. The main difference between a SplFixedArray and a normal PHP array is that the SplFixedArray must be resized manually and allows only integers within the range as indexes. The advantage is that it uses less memory than a standard array.

Class synopsis

class SplFixedArray implements Iterator, ArrayAccess, Countable {

/* Methods */

public __construct(int $size = 0)

public count(): int

public current(): mixed

public static fromArray(array $array, bool $preserveKeys = true): SplFixedArray

public getSize(): int

public key(): int

public next(): void

public offsetExists(int $index): bool

public offsetGet(int $index): mixed

public offsetSet(int $index, mixed $value): void

public offsetUnset(int $index): void

public rewind(): void

public setSize(int $size): bool

public toArray(): array

public valid(): bool

public __wakeup(): void

}

Examples

Example #1 SplFixedArray usage example

<?php
// Initialize the array with a fixed length
$array = new SplFixedArray(5);

$array[1] = 2;
$array[4] = "foo";

var_dump($array[0]); // NULL
var_dump($array[1]); // int(2)

var_dump($array["4"]); // string(3) "foo"

// Increase the size of the array to 10
$array->setSize(10);

$array[9] = "asdf";

// Shrink the array to a size of 2
$array->setSize(2);

// The following lines throw a RuntimeException: Index invalid or out of range
try {
    var_dump($array["non-numeric"]);
} catch(RuntimeException $re) {
    echo "RuntimeException: ".$re->getMessage()."\n";
}

try {
    var_dump($array[-1]);
} catch(RuntimeException $re) {
    echo "RuntimeException: ".$re->getMessage()."\n";
}

try {
    var_dump($array[5]);
} catch(RuntimeException $re) {
    echo "RuntimeException: ".$re->getMessage()."\n";
}
?>

The above example will output:

NULL
int(2)
string(3) "foo"
RuntimeException: Index invalid or out of range
RuntimeException: Index invalid or out of range
RuntimeException: Index invalid or out of range

Table of Contents

• SplFixedArray::__construct — Constructs a new fixed array
• SplFixedArray::count — Returns the size of the array
• SplFixedArray::current — Return current array entry
• SplFixedArray::fromArray — Import a PHP array in a SplFixedArray instance
• SplFixedArray::getSize — Gets the size of the array
• SplFixedArray::key — Return current array index
• SplFixedArray::next — Move to next entry
• SplFixedArray::offsetExists — Returns whether the requested index exists
• SplFixedArray::offsetGet — Returns the value at the specified index
• SplFixedArray::offsetSet — Sets a new value at a specified index
• SplFixedArray::offsetUnset — Unsets the value at the specified $index
• SplFixedArray::rewind — Rewind iterator back to the start
• SplFixedArray::setSize — Change the size of an array
• SplFixedArray::toArray — Returns a PHP array from the fixed array
• SplFixedArray::valid — Check whether the array contains more elements
• SplFixedArray::__wakeup — Reinitialises the array after being unserialised

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https://www.php.net/manual/en/class.splfixedarray.php