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php method to filter invisible characters: first create a PHP code sample file; then define a "filterNonPrintableChar" method; then implement filtering logic through isset, ord and other functions; finally output the filtering results through "var_dump" Can.
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php filter invisible characters
Coding knowledge
ASCII codes are reserved for standard symbols, numbers, English, etc. The value range is 0~127, and some are extended ASCII codes 128~255. When the operating system uses non-ASCII encoding (such as Chinese character encoding), extended ASCII code is generally used. It is agreed to use a coding range of 128 to 255 for 2 to 3 or even 4 consecutive bytes to encode Chinese characters.
So you can judge whether the ASCII code decimal value is greater than 127 to filter out Chinese characters.
php code
<?php /** * @param $str * @return string * 过滤不可见字符,支持中文过滤 * 0至31和127这33个编码是不可见的特殊字符(控制符) */ function filterNonPrintableChar($str) { $i = 0; $newStr = ''; while (isset($str[$i])) { $char = $str[$i]; $asc = ord($char); if ($asc > 31 && $asc < 127 || $asc > 127) { $newStr .= $char; } $i++; } return $newStr; } $str = chr(1) ."a3#2%1". chr(2) . chr(54) . "s哈哈ad~a好的s"; var_dump(filterNonPrintableChar($str)); $str = "“ASCII码为标准符号、数字、英文等进行了保留,取值范围是0~127,还有一部分作为扩展ASCII码128~255当操作系统采用非ASCII编码时(比如汉字编码),一般用扩展ASCII码来进行,约定用128~255范围的编码连续2~3甚至4个来进行...”"; var_dump(filterNonPrintableChar($str));
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