Str_Replace与数组大写和数字（PHP）

Question

我有一个简单的代码，但我无法正常工作。

$String = 'abc123ABC';

$Replace_From = array("a","b","c","1","2","3","A","B","C");
$Replace_To   = array("A","B","C","a","b","c","1","2","3");

$NewString = str_replace($Replace_From, $Replace_To, $String);
echo $NewString;

• 正确的结果：ABCabc123
• 但是我的代码返回了这个结果：123abc123！

感谢您的帮助！

Answer 1

str_replace将替换所有出现的字母，因此如果我们将代码拆分为2，我们可以更多地了解会发生什么：

<?php
$String = 'abc123ABC';

$Replace_From = array("a","b","c","1","2","3");
$Replace_To   = array("A","B","C","a","b","c");

$FirstString = str_replace($Replace_From, $Replace_To, $String);
echo $FirstString . '<br>';

$Replace_From = array("A","B","C");
$Replace_To   = array("1","2","3");

$SecondString = str_replace($Replace_From, $Replace_To, $FirstString);
echo $SecondString;

$FirstString = 'ABCabcABC'所以'A'将被1替换两次，因此'B'替代'C'。