PHP string function (1): length calculation

* 1.strlen($str)

* 2.mb_strlen($str, $encoding)

$siteName = 'php中文网';

//Get the internal character encoding set

$encoding =   mb_internal_encoding();
echo '内部字符编码集: ',$encoding,'
';

/ /1.strlen($str): Get the string length represented by bytes

//In utf8 mode, a Chinese character is represented by three bytes

echo strlen($siteName),'
';

//2.mb_strlen ($str, $encoding): Get the length represented by the number of characters

echo mb_strlen($siteName, $encoding),'
';

//Omit the second parameter, the system default character encoding set will be used, which is currently utf-8

echo mb_strlen($siteName),'
';  //返回值不变