5_PHP数组_3_数组处理函数及其应用_3_数组指针函数

以下为学习孔祥盛主编的《PHP编程基础与实例教程》（第二版）所做的笔记。

数组指针函数

1. key() 函数

程序：

<?php
$interests[2] = "music";
$interests[5] = "movie";
$interests[1] = "computer";
$interests[] = "software";
var_dump(key($interests));  //int 2 //返回数组 arr 中"当前指针"所指元素的键名。
?>

输出：

D:wampServerwwwApache服务器主目录practise例程.php:6:int 2

2. current() 函数

程序：

<?php
$interests[2] = "music";
$interests[5] = "movie";
$interests[1] = "computer";
$interests[] = "software";
var_dump(current($interests));  //string 'music' (length=5) //返回数组 arr 中“当前指针”所指元素的“值”
?>

输出：

D:wampServerwwwApache服务器主目录practise例程.php:6:string 'music' (length=5)

3. next() 函数

程序：

<?php
$interests[2] = "music";
$interests[5] = "movie";
$interests[1] = "computer";
$interests[] = "software";
$second = next($interests);
$third  = next($interests);
var_dump(key($interests));  //int  1
echo "<br/>";
var_dump(current($interests));  //string 'computer' (length=8)
echo "<br/>";
var_dump($second);  //string 'movie' (length=5)
echo "<br/>";
var_dump($third);   //string 'computer' (length=8)
?>

输出：

D:wampServerwwwApache服务器主目录practise例程.php:8:int 1

D:wampServerwwwApache服务器主目录practise例程.php:10:string 'computer' (length=8)

D:wampServerwwwApache服务器主目录practise例程.php:12:string 'movie' (length=5)

D:wampServerwwwApache服务器主目录practise例程.php:14:string 'computer' (length=8)

4. end() 函数

程序：

<?php
$interests[2] = "music";
$interests[5] = "movie";
$interests[1] = "computer";
$interests[] = "software";
$end = end($interests);
var_dump(key($interests));      //int 6
echo "<br/>";
var_dump(current($interests));  //string 'software' (length=8)
echo "<br/>";
var_dump($end);                 //string 'software' (length=8)
?>

输出：

D:wampServerwwwApache服务器主目录practise例程.php:7:int 6

D:wampServerwwwApache服务器主目录practise例程.php:9:string 'software' (length=8)

D:wampServerwwwApache服务器主目录practise例程.php:11:string 'software' (length=8)

5. prev() 函数

 程序：

<?php
$interests[2] = "music";
$interests[5] = "movie";
$interests[1] = "computer";
$interests[] = "software";
$end = end($interests);
$prev = prev($interests);
var_dump(key($interests));  //int 1
echo "<br/>";
var_dump(current($interests));  //string 'computer' (length=8)
echo "<br/>";
var_dump($end);     //string 'software' (length=8)
echo "<br/>";
var_dump($prev);    //string 'computer' (length=8)
?>

 输出：

D:wampServerwwwApache服务器主目录practise例程.php:8:int 1

D:wampServerwwwApache服务器主目录practise例程.php:10:string 'computer' (length=8)

D:wampServerwwwApache服务器主目录practise例程.php:12:string 'software' (length=8)

D:wampServerwwwApache服务器主目录practise例程.php:14:string 'computer' (length=8)

6. reset() 函数

 程序：

<?php
$interests[2] = "music";
$interests[5] = "movie";
$interests[1] = "computer";
$interests[] = "software";
$end = end($interests);
$first = reset($interests);
var_dump(key($interests));  //int 2
echo "<br/>";
var_dump(current($interests));  //string 'music' (length=5)
echo "<br/>";
var_dump($end);     //string 'software' (length=8)
echo "<br/>";
var_dump($first);   //string 'music' (length=5)
?>

 输出：

D:wampServerwwwApache服务器主目录practise例程.php:8:int 2

D:wampServerwwwApache服务器主目录practise例程.php:10:string 'music' (length=5)

D:wampServerwwwApache服务器主目录practise例程.php:12:string 'software' (length=8)

D:wampServerwwwApache服务器主目录practise例程.php:14:string 'music' (length=5)

7. each() 函数

 程序：

<?php
$interests[2] = "music";
$interests[5] = "movie";
$interests[1] = "computer";
$interests[] = "software";
$each = each($interests);
print_r( $each );   //Array ( [1] => music [value] => music [0] => 2 [key] => 2 )
echo "<br/>";
echo current($interests);   //movie
?>

 输出：

说明：

　　PHP 7.2 废弃了each（）方法。

数组的遍历

使用list()语言结构、each()函数和循环语句可以实现

程序：

<?php
$fruits = array( 'orange', 'apple', 'banana');
$colors = array( 'orange', 'red', 'yellow' );
$temp = array_combine( $fruits,$colors );
do{
    $key = key($temp);
    $value = current($temp);
    echo $key." => ".$value."<br/>";
}while( next($temp) );
?>

输出：

orange => orange
apple => red
banana => yellow