我无法在PHP上更改字符串编码

问题描述：

<?php
   $str = "Text";
   $str = mb_convert_encoding($str, "UTF-8", mb_detect_encoding($str));
   echo mb_detect_encoding($str);
?>

This code is givin me "ASCII" as output. Why?

答

Your string has no UTF-8 specific characters, only ASCII.

Add one in:

$str = "Text È";
$str = mb_convert_encoding($str, "UTF-8", mb_detect_encoding($str));
echo mb_detect_encoding($str);

You'll get UTF-8 as output now, as seen in this demo.

However, you don't need to run the conversion to get UTF-8 as output, mb_detect_encoding() picks up that the string is UTF-8 without this step.

答

My assumption is that because ASCII is a subset of UTF-8, that a purely ASCII "converted" to UTF-8 will be indistinguishable from ASCII.