The SplFixedArray class

(PHP 5 >= 5.3.0, PHP 7)

简介

The SplFixedArray class provides the main functionalities of array. The main differences between a SplFixedArray and a normal PHP array is that the SplFixedArray is of fixed length and allows only integers within the range as indexes. The advantage is that it uses less memory than a standard array.

类摘要

SplFixedArray implements Iterator , ArrayAccess , Countable {
/* 方法 */
public __construct ([ int $size = 0 ] )
public count ( ) : int
public current ( ) : mixed
public static fromArray ( array $array [, bool $save_indexes = 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 $newval ) : void
public offsetUnset ( int $index ) : void
public rewind ( ) : void
public setSize ( int $size ) : bool
public toArray ( ) : array
public valid ( ) : bool
public __wakeup ( ) : void
}

范例

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";
}
?>

以上例程会输出：

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

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