PHP Ds Deque apply()函数用法介绍

Ds \ Deque :: apply()function是PHP中的内置函数, 用于通过执行回调函数定义的操作来更新Deque的值。

语法如下：

public Ds\Deque::apply( $callback ) : void

参数：该函数接受单个参数$ callback包含该函数的函数定义了要对双端队列的每个元素执行的操作。

返回值：此函数不返回任何值。

下面的程序说明了Ds \ Deque :: apply()PHP中的功能：

程序1：

<?php
  
// Declare deque
$deck = new \Ds\Deque([1, 2, 3, 4, 5, 6]);
  
echo ( "\nElements in the deque are\n" );
  
// Display the deque elements
print_r( $deck );
  
// Use apply() function to implement
// the operation
$deck ->apply( function ( $element ) { 
     return $element * 10; 
});
  
echo ( "\nUpdated elements in the deque\n" );
  
// Display the deque elements
print_r( $deck );
  
?>

输出如下：

Elements in the deque are
Ds\Deque Object
(
    [0] => 1
    [1] => 2
    [2] => 3
    [3] => 4
    [4] => 5
    [5] => 6
)

Updated elements in the deque
Ds\Deque Object
(
    [0] => 10
    [1] => 20
    [2] => 30
    [3] => 40
    [4] => 50
    [5] => 60
)

程式2：

<?php
  
// Declare deque
$deck = new \Ds\Deque([10, 20, 30, 40, 50, 60]);
  
echo ( "\nElements in the deque are\n" );
  
// Display the deque elements
print_r( $deck );
  
// Use apply() function to implement
// the operation
$deck ->apply( function ( $element ) { 
     return $element % 10; 
});
  
echo ( "\nUpdated elements in the deque\n" );
  
// Display the deque elements
print_r( $deck );
  
?>

输出如下：

Elements in the deque are
Ds\Deque Object
(
    [0] => 10
    [1] => 20
    [2] => 30
    [3] => 40
    [4] => 50
    [5] => 60
)

Updated elements in the deque
Ds\Deque Object
(
    [0] => 0
    [1] => 0
    [2] => 0
    [3] => 0
    [4] => 0
    [5] => 0
)

参考： http://php.net/manual/en/ds-deque.apply.php

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