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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php把负数转为正整数的方法:1、使用abs()函数将负数转为正数,使用intval()函数对正数取整,转为正整数,语法“intval(abs($number))”;2、利用“~”位运算符将负数取反加一,语法“~$number + 1”。

实现方法:1、使用“sleep(延迟秒数)”语句,可延迟执行函数若干秒;2、使用“time_nanosleep(延迟秒数,延迟纳秒数)”语句,可延迟执行函数若干秒和纳秒;3、使用“time_sleep_until(time()+7)”语句。

php除以100保留两位小数的方法:1、利用“/”运算符进行除法运算,语法“数值 / 100”;2、使用“number_format(除法结果, 2)”或“sprintf("%.2f",除法结果)”语句进行四舍五入的处理值,并保留两位小数。

判断方法:1、使用“strtotime("年-月-日")”语句将给定的年月日转换为时间戳格式;2、用“date("z",时间戳)+1”语句计算指定时间戳是一年的第几天。date()返回的天数是从0开始计算的,因此真实天数需要在此基础上加1。

方法:1、用“str_replace(" ","其他字符",$str)”语句,可将nbsp符替换为其他字符;2、用“preg_replace("/(\s|\ \;||\xc2\xa0)/","其他字符",$str)”语句。

php判断有没有小数点的方法:1、使用“strpos(数字字符串,'.')”语法,如果返回小数点在字符串中第一次出现的位置,则有小数点;2、使用“strrpos(数字字符串,'.')”语句,如果返回小数点在字符串中最后一次出现的位置,则有。

在PHP中,可以利用implode()函数的第一个参数来设置没有分隔符,该函数的第一个参数用于规定数组元素之间放置的内容,默认是空字符串,也可将第一个参数设置为空,语法为“implode(数组)”或者“implode("",数组)”。

在php中,可以使用substr()函数来读取字符串后几个字符,只需要将该函数的第二个参数设置为负值,第三个参数省略即可;语法为“substr(字符串,-n)”,表示读取从字符串结尾处向前数第n个字符开始,直到字符串结尾的全部字符。


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