PHP prev() 函数
PHP 教程
· 2019-01-22 21:42:03
实例
输出数组中的当前元素、下一个元素和上一个元素的值：
<?php
$people = array("Peter", "Joe", "Glenn", "Cleveland");
echo current($people) . "<br>";
echo next($people) . "<br>";
echo prev($people);
?>
$people = array("Peter", "Joe", "Glenn", "Cleveland");
echo current($people) . "<br>";
echo next($people) . "<br>";
echo prev($people);
?>
定义和用法
prev() 函数将内部指针指向数组中的上一个元素，并输出。
相关的方法：
- next() - 将内部指针指向数组中的下一个元素，并输出。
- current() - 返回数组中的当前元素的值。
- end() - 将内部指针指向数组中的最后一个元素，并输出。
- reset() - 将内部指针指向数组中的第一个元素，并输出。
- each() - 返回当前元素的键名和键值，并将内部指针向前移动。
语法
prev(array)
| 参数 | 描述 |
|---|---|
| array | 必需。规定要使用的数组。 |
技术细节
| 返回值： | 如果成功则返回数组中上一个元素的值，如果没有更多的数组元素则返回 FALSE。 |
|---|---|
| PHP 版本： | 4+ |
更多实例
实例 1
所有相关方法的演示：
<?php
$people = array("Peter", "Joe", "Glenn", "Cleveland");
echo current($people) . "<br>"; // The current element is Peter
echo next($people) . "<br>"; // The next element of Peter is Joe
echo current($people) . "<br>"; // Now the current element is Joe
echo prev($people) . "<br>"; // The previous element of Joe is Peter
echo end($people) . "<br>"; // The last element is Cleveland
echo prev($people) . "<br>"; // The previous element of Cleveland is Glenn
echo current($people) . "<br>"; // Now the current element is Glenn
echo reset($people) . "<br>"; // Moves the internal pointer to the first element of the array, which is Peter
echo next($people) . "<br>"; // The next element of Peter is Joe
print_r (each($people)); // Returns the key and value of the current element (now Joe), and moves the internal pointer forward
?>
$people = array("Peter", "Joe", "Glenn", "Cleveland");
echo current($people) . "<br>"; // The current element is Peter
echo next($people) . "<br>"; // The next element of Peter is Joe
echo current($people) . "<br>"; // Now the current element is Joe
echo prev($people) . "<br>"; // The previous element of Joe is Peter
echo end($people) . "<br>"; // The last element is Cleveland
echo prev($people) . "<br>"; // The previous element of Cleveland is Glenn
echo current($people) . "<br>"; // Now the current element is Glenn
echo reset($people) . "<br>"; // Moves the internal pointer to the first element of the array, which is Peter
echo next($people) . "<br>"; // The next element of Peter is Joe
print_r (each($people)); // Returns the key and value of the current element (now Joe), and moves the internal pointer forward
?>
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