php - PHP 中 str_replace 的性能

Question

这里我有 2 个方法使用 str_replace 来替换给定短语中的字符串。

// Method 1
$phrase  = "You should eat fruits, vegetables, and fiber every day.";
$healthy = array("fruits", "vegetables", "fiber");
$yummy   = array("pizza", "beer", "ice cream");
$phrase = str_replace($healthy, $yummy, $phrase);

// Method 2
$phrase  = "You should eat fruits, vegetables, and fiber every day.";
$phrase = str_replace("fruits", "pizza", $phrase);
$phrase = str_replace("vegetables", "beer", $phrase);
$phrase = str_replace("fiber", "ice cream", $phrase);

哪种方法更有效(在执行时间和使用的资源方面)？

假设真实的短语要长得多(例如 50,000 个字符)，并且要替换的单词有更多的对。

我的想法是，方法2调用了3次str_replace，函数调用的开销会更大；另一方面，方法 1 创建 2 个数组，str_replace 需要在运行时解析 2 个数组。

Answer 1

我更愿意使用方法 1，因为它更清晰、更有条理，方法 1 也提供了使用来自其他来源的对的机会，例如:数据库中的坏词表。方法 2 需要另一个排序循环..

<?php
$time_start = microtime(true);
for($i=0;$i<=1000000;$i++){
    // Method 1
    $phrase  = "You should eat fruits, vegetables, and fiber every day.";
    $healthy = array("fruits", "vegetables", "fiber");
    $yummy   = array("pizza", "beer", "ice cream");
    $phrase = str_replace($healthy, $yummy, $phrase);
}
$time_end = microtime(true);
$time = $time_end - $time_start;
echo "Did Test 1 in ($time seconds)\n<br />";



$time_start = microtime(true);
for($i=0;$i<=1000000;$i++){
    // Method2
    $phrase  = "You should eat fruits, vegetables, and fiber every day.";
    $phrase = str_replace("fruits", "pizza", $phrase);
    $phrase = str_replace("vegetables", "beer", $phrase);
    $phrase = str_replace("fiber", "ice cream", $phrase);

}
$time_end = microtime(true);
$time = $time_end - $time_start;
echo "Did Test 2 in ($time seconds)\n";
?>  

在(3.6321988105774 秒)内完成测试 1

在(2.8234610557556 秒)内完成测试 2

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编辑: 进一步测试字符串重复到 50k，更少的迭代和来自 ajreal 的建议，差异是如此微小。

<?php
$phrase  = str_repeat("You should eat fruits, vegetables, and fiber every day.",50000);
$healthy = array("fruits", "vegetables", "fiber");
$yummy   = array("pizza", "beer", "ice cream");

$time_start = microtime(true);
for($i=0;$i<=10;$i++){
    // Method 1
    $phrase = str_replace($healthy, $yummy, $phrase);
}
$time_end = microtime(true);
$time = $time_end - $time_start;
echo "Did Test 1 in ($time seconds)\n<br />";



$time_start = microtime(true);
for($i=0;$i<=10;$i++){
    // Method2
    $phrase = str_replace("fruits", "pizza", $phrase);
    $phrase = str_replace("vegetables", "beer", $phrase);
    $phrase = str_replace("fiber", "ice cream", $phrase);

}
$time_end = microtime(true);
$time = $time_end - $time_start;
echo "Did Test 2 in ($time seconds)\n";
?>  

在(1.1450328826904 秒)内完成测试 1

在(1.3119208812714 秒)内完成测试 2