


In "Learning PHP & MYSQL - Character Encoding (Part 1)", the conversion relationship between Unicode and UTF-8 is introduced, and a UTF-8 encoding rule is summarized. Based on this encoding rule, a UTF-8 encoding parsing program is written. , the following is the implementation of PHP:
/*
Program function, $str is a UTF-8 encoded string mixed with Chinese and English.
Decode and display this string correctly according to UTF-8 encoding rules.
*/
$str = 'Today is very happy, so we decided to go to KFC to eat Coke chicken wings!!!';
/*
$str is to be intercepted The string
$len is the number of intercepted characters
*/
function utf8sub($str,$len) {
if($len return '' ;
}
$offset = 0; // Offset when intercepting high-order bytes
$chars = 0; // Number of characters intercepted
$res = '' ; // Store the intercepted result string
while($chars // Take the first byte of the string first
// Convert it to decimal
// Then convert to binary
$high = ord(substr($str,$offset,1));
// echo '$high='. $high .'
';
if($high == null ){ // If the high bit is null, it proves that it has been fetched to the end, break directly
break;
}
if( ($high>>2) === 0x3F){ // Shift the high bit to the right by 2 bits and compare it with binary 111111. If it is the same, take 6 bytes
// Intercept 2 bytes
$count = 6;
}else if(($high>>3) === 0x1F){ // Shift the high bit to the right by 2 bits and compare it with binary 11111. If it is the same, take 5 bytes
// Intercept 3 bytes
$count = 5;
}else if(($high>>4) === 0xF){ // Shift the high bit to the right by 2 bits and compare it with binary 1111. If they are the same, then Take 4 bytes
// Take 4 bytes
$count = 4;
}else if(($high>>5) === 0x7){ // Will Shift the high bit right by 2 bits and compare with binary 111. If it is the same, take 3 bytes
// Intercept 5 bytes
$count = 3;
}else if(($high> >6) === 0x3){ // Shift the high bit to the right by 2 bits, compare with binary 11, if the same, take 2 bytes
// Intercept 6 bytes
$count = 2;
}else if(($high>>7) === 0x0){ // Shift the high bit to the right by 2 bits and compare it with binary 0. If they are the same, take 1 byte
$count = 1;
}
// echo '$count='.$count.'
';
$res .= substr($str,$offset,$count); / / Take out a character and connect it to $res string
$chars += 1; // Number of intercepted characters + 1
$offset += $count; // Intercept the high offset and move it backward by $count Bytes
}
return $res;
}
echo utf8sub($str,100);

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。

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。

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。

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)”。

php字符串有下标。在PHP中,下标不仅可以应用于数组和对象,还可应用于字符串,利用字符串的下标和中括号“[]”可以访问指定索引位置的字符,并对该字符进行读写,语法“字符串名[下标值]”;字符串的下标值(索引值)只能是整数类型,起始值为0。


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