PHP 中 FOR 与 FOREACH 的性能对比
phpserver side programmingprogramming更新于 2025/8/5 7:22:17
与 'for' 循环相比，'foreach' 速度较慢。foreach 会复制需要执行迭代的数组。
为了提高性能，需要使用引用的概念。此外，'foreach' 也易于使用。
示例
以下是一个简单的代码示例 −
<?php
$my_arr = array();
for ($i = 0; $i < 10000; $i++) {
$my_arr[] = $i;
}
$start = microtime(true);
foreach ($my_arr as $k => $v) {
$my_arr[$k] = $v + 1;
}
echo "This completed in ", microtime(true) - $start, " seconds";
echo "<br>";
$start = microtime(true);
foreach ($my_arr as $k => &$v) {
$v = $v + 1;
}
echo "This completed in ", microtime(true) - $start, " seconds";
echo "<br>";
$start = microtime(true);
foreach ($my_arr as $k => $v) {}
echo "This completed in ", microtime(true) - $start, " seconds";
echo "<br>";
$start = microtime(true);
foreach ($my_arr as $k => &$v) {}
echo "This completed in ", microtime(true) - $start, " seconds";
?>
输出
这将产生以下输出 −
This completed in 0.00058293342590332 seconds This completed in 0.00063300132751465 seconds This completed in 0.00023412704467773 seconds This completed in 0.00026583671569824 seconds
