For example,
$testStr = 'Hello, please help'; // It is in utf-8 format $testStr is a variable, so I don’t know if it is There is no garbled code, and the garbled code is somewhere, so the method of removing it by interception does not seem to work.

$testStr1 = json_encode($testStr);

var_dump($testStr1);

prints as false

It’s because there are garbled characters. How to parse the string with garbled characters? Please give me some advice. Thank you.