PHP strlen和mb_strlen的區(qū)別
Jun 08, 2016 pm 05:24 PM我初步理解是strlen只能計(jì)算英文字符,而mb_strlen是可以計(jì)算中文與英文字符的長(zhǎng)度,下面我來(lái)詳細(xì)的介紹 strlen和mb_strlen的區(qū)別.
定義和用法
strlen() 函數(shù)返回字符串的長(zhǎng)度。
語(yǔ)法
strlen(string)參數(shù) 描述
string 必需。規(guī)定要檢查的字符串。
而mb_strlen()函數(shù)的參考也是一樣的。
例子
?代碼如下 | 復(fù)制代碼 |
$str=‘中文a字1符‘; |
結(jié)果分析:在strlen計(jì)算時(shí),對(duì)待一個(gè)UTF8的中文字符是3個(gè)長(zhǎng)度,所以“中文a字1符”長(zhǎng)度是3*4+2=14
在mb_strlen計(jì)算時(shí),選定內(nèi)碼為UTF8,則會(huì)將一個(gè)中文字符當(dāng)作長(zhǎng)度1來(lái)計(jì)算,所以“中文a字1符”長(zhǎng)度是6
PHP內(nèi)置的字符串長(zhǎng)度函數(shù)strlen無(wú)法正確處理中文字符串,它得 到的只是字符串所占的字節(jié)數(shù)。對(duì)于GB2312的中文編碼,strlen得到的值是漢字個(gè)數(shù)的2倍,而對(duì)于UTF-8編碼的中文,就是3倍的差異了(在 UTF-8編碼下,一個(gè)漢字占3個(gè)字節(jié))。
采用mb_strlen函數(shù)可以較好地解決這個(gè)問(wèn)題。mb_strlen的用法和 strlen類(lèi)似,只不過(guò)它有第二個(gè)可選參數(shù)用于指定字符編碼。例如得到UTF-8的字符串$str長(zhǎng)度,可以用 mb_strlen($str,'UTF-8')。如果省略第二個(gè)參數(shù),則會(huì)使用PHP的內(nèi)部編碼。
注意事項(xiàng)
php默認(rèn)是不支持mb_strlen()函數(shù)的,需要安裝擴(kuò)展模塊。安裝方法如下:
?代碼如下 | 復(fù)制代碼 |
yum install php-mbstring |
找到mbstring.so的位置,可以使用rpm -ql 安裝的rpm名
修改/etc/php.ini配置文件,增加
?代碼如下 | 復(fù)制代碼 |
extension=php_mbstring.so |
并確保php_mbstring.so模塊在extension_dir = "/usr/lib64/php/modules"配置所指的路徑里。

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