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PHP SPL标准库之SplFixedArray使用实例_PHP

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Release: 2016-06-01 11:05:47
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SplFixedArray主要是处理数组相关的主要功能,与普通php array不同的是,它是固定长度的,且以数字为键名的数组,优势就是比普通的数组处理更快。

看看我本机的Benchmark测试:

ini_set('memory_limit','12800M');
 
for($size = 10000; $size < 10000000; $size *= 4) {
  echo PHP_EOL . "Testing size: $size" . PHP_EOL;
  for($s = microtime(true), $container = Array(), $i = 0; $i < $size; $i++) $container[$i] = NULL;
  echo "Array(): " . (microtime(true) - $s) . PHP_EOL;
 
  for($s = microtime(true), $container = new SplFixedArray($size), $i = 0; $i < $size; $i++) $container[$i] = NULL;
  echo "SplArray(): " . (microtime(true) - $s) . PHP_EOL;
}
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结果如下:

Testing size: 10000
Array(): 0.004000186920166
SplArray(): 0.0019998550415039
 
Testing size: 40000
Array(): 0.017001152038574
SplArray(): 0.0090007781982422
 
Testing size: 160000
Array(): 0.050002098083496
SplArray(): 0.046003103256226
 
Testing size: 640000
Array(): 0.19701099395752
SplArray(): 0.16700983047485
 
Testing size: 2560000
Array(): 0.75704312324524
SplArray(): 0.67303895950317

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通常情况下SplFixedArray要比php array快上20%~30%,所以如果你是处理巨大数量的固定长度数组,还是强烈建议使用。
SplFixedArray类摘要如下:

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

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使用SplFixedArray:

$arr = new SplFixedArray(4);
$arr[0] = 'php';
$arr[1] = 1;
$arr[3] = 'python';
 
//遍历, $arr[2] 为null
foreach($arr as $v) {
  echo $v . PHP_EOL;
}
 
//获取数组长度
echo $arr->getSize(); //4
 
//增加数组长度
$arr->setSize(5);
$arr[4] = 'new one';
 
//捕获异常
try{
  echo $arr[10];
} catch (RuntimeException $e) {
  echo $e->getMessage();
} 
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