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这些函数的行为受 php.ini 中的设置影响。

mbstring 配置选项
名字 默认 可修改范围 更新日志
mbstring.language "neutral" PHP_INI_ALL  
mbstring.detect_order NULL PHP_INI_ALL  
mbstring.http_input "pass" PHP_INI_ALL 已弃用
mbstring.http_output "pass" PHP_INI_ALL 已弃用
mbstring.internal_encoding NULL PHP_INI_ALL 已弃用
mbstring.substitute_character NULL PHP_INI_ALL  
mbstring.func_overload "0" PHP_INI_SYSTEM 自 PHP 7.2.0 起弃用,PHP 8.0.0 起删除。
mbstring.encoding_translation "0" PHP_INI_PERDIR  
mbstring.http_output_conv_mimetypes "^(text/|application/xhtml\+xml)" PHP_INI_ALL  
mbstring.strict_detection "0" PHP_INI_ALL  
mbstring.regex_retry_limit "1000000" PHP_INI_ALL 自 PHP 7.4.0 起可用。
mbstring.regex_stack_limit "100000" PHP_INI_ALL 自 PHP 7.3.5 起可用。
有关 PHP_INI_* 样式的更多详情与定义,见 配置可被设定范围


mbstring.language string

mbstring 使用了国家默认语言设置(NLS)。 注意,该选项自动地定义了 mbstring.internal_encodingmbstring.internal_encoding,在 php.ini 里应当放置在 mbstring.language 之后。

mbstring.encoding_translation bool

为传入的 HTTP 查询启用透明字符编码过滤器,将检测和转换输入的编码为内部字符编码(internal character encoding)。

mbstring.internal_encoding string



用户应该将此选项留空,并设置 default_charset 作为代替。

mbstring.http_input string


定义 HTTP 输入字符的默认编码。

用户应该将此选项留空,并设置 default_charset 作为代替。

mbstring.http_output string


定义 HTTP 输出字符的默认编码。

用户应该将此选项留空,并设置 default_charset 作为代替。

mbstring.detect_order string

定义字符编码的默认检测顺序。参见 mb_detect_order()

mbstring.substitute_character string

为无效编码的字符定义替代字符。 参见 mb_substitute_character() ,查看支持的值。

mbstring.func_overload string

本特性自 PHP 7.2.0 起废弃,并且自 PHP 8.0.0 起被移除。 强烈建议不要使用本特性。

用 mbstring 对应的函数覆盖单字节版本的函数集。更多信息参见函数的覆盖

该设置仅能通过 php.ini 文件来修改。

mbstring.http_output_conv_mimetypes string

mbstring.strict_detection bool

使用严格的编码检测。有关描述和示例,参见 mb_detect_encoding()

mbstring.regex_retry_limit int

Limits the amount of backtracking that may be performed during one mbregex match.

此设置仅在链接的 oniguruma >= 6.8.0 时生效。

mbstring.regex_stack_limit int

限制 mbstring 正则表达式的栈深度。

根据 » HTML4.01 规范,允许 Web 浏览器以页面不同的字符编码来提交表单。参见用 mb_http_input() 来检测浏览器使用的字符编码。

尽管流行的浏览器能够根据给出的 HTML 文档合理猜测正确的编码,但如果能通过 header() 函数在 HTTP 的 Content-Type 头内或 ini 的 default_charset 里设置适当的 charset 参数则会更佳。

示例 #1 php.ini 设置例子

; 设置默认语言
mbstring.language        = Neutral; 设置默认语言 Neutral(UTF-8) (默认的值)
mbstring.language        = English; 设置默认语言为 English 
mbstring.language        = Japanese; 设置默认语言为 Japanese

;; 设置内部的默认编码
;; 注意:请确保这个编码能被 PHP 所处理
mbstring.internal_encoding    = UTF-8  ; 设置内部的默认编码为 UTF-8

;; 启用 HTTP 输入编码的转换
mbstring.encoding_translation = On

;; 设置 HTTP 输入的默认编码
;; 注意:脚本不能修改 http_input 的设置
mbstring.http_input           = pass    ; 不转换
mbstring.http_input           = auto    ; 设置 HTTP 输入为 auto
                                ; "auto" 会根据 mbstring.language 自动扩展
mbstring.http_input           = SJIS    ; 设置 HTTP 输入编码为 SJIS
mbstring.http_input           = UTF-8,SJIS,EUC-JP ; 指定顺序

;; 设置 HTTP 输出的默认编码
mbstring.http_output          = pass    ; 不转换
mbstring.http_output          = UTF-8   ; 设置 HTTP 输出编码为 UTF-8

;; 设置字符编码的默认检测顺序
mbstring.detect_order         = auto    ; Set detect order to auto
mbstring.detect_order         = ASCII,JIS,UTF-8,SJIS,EUC-JP ; Specify order

;; 设置默认的替代字符
mbstring.substitute_character = 12307   ; 指定 Unicode 值
mbstring.substitute_character = none    ; 不打印字符
mbstring.substitute_character = long    ; Long 的例子: U+3000,JIS+7E7E

示例 #2 php.iniEUC-JP 用户的设置

;; 禁用输出缓冲
output_buffering      = Off

;; 设置 HTTP header 字符编码
default_charset       = EUC-JP    

;; 设置默认语言为 Japanese
mbstring.language = Japanese

;; 启用 HTTP 输入编码的转换
mbstring.encoding_translation = On

;; 启用 HTTP 输入转换的编码为 auto
mbstring.http_input   = auto 

;; 转换 HTTP 输出的编码为 EUC-JP
mbstring.http_output  = EUC-JP    

;; 设置内部编码为 EUC-JP
mbstring.internal_encoding = EUC-JP    

;; 不要打印无效的字符
mbstring.substitute_character = none   

示例 #3 php.iniSJIS 用户的设置

;; 启用输出缓冲
output_buffering     = On

;; 设置 mb_output_handler 来启用输出编码的转换
output_handler       = mb_output_handler

;; 设置 HTTP header 的字符编码
default_charset      = Shift_JIS

;; 设置默认语言为 Japanese
mbstring.language = Japanese

;; 设置 http 输入转换的编码为 auto
mbstring.http_input  = auto 

;; 转换成 SJIS
mbstring.http_output = SJIS    

;; 设置内部变量为 EUC-JP
mbstring.internal_encoding = EUC-JP    

;; 不要打印无效的字符
mbstring.substitute_character = none   

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User Contributed Notes 3 notes

Hayley Watson
4 years ago
String literals in the PHP script are encoded with the same encoding that the PHP file was saved with. This is not affected by default_charset or other .ini settings.

Scenario: The default_charset is KOI8-R, and there is a text file "input.txt" containing the string "Это текст для поиска." in KOI8-R encoding.

A PHP script is written:

// mb_internal_encoding('KOI8-R');

$string  = 'текст.';

$data = file_get_contents('input.txt');

mb_strpos($data, $string);

But unfortunately it was saved as UTF-8.

It doesn't work; mb_strpos() returns false because it can't find the UTF-8-encoded "текст" inside the KOI8-R-encoded "Это текст для поиска.".

Adjusting the default_charset had no effect. Not even fiddling with mb_internal_encoding could fix it, simply because the strings involved had *different* encodings and without actually changing one of them they just weren't going to match.

Either re-save the source file as KOI8-R to match the data file, or re-save the data file as UTF-8 to match the source code. Only then will the script properly echo '4'.
ASchmidt at Anamera dot net
4 years ago
The documentation is vague, on WHAT precisely the valid "NLS" language strings are that are valid for "mbstring.language".

According to http://php.net/manual/en/function.mb-language.php the values are "Japanese", "ja", "English", "en", or "uni" for UTF-8.
On the other hand, the sample on this current page omits "uni" but introduces "Neutral" as an undocumented option - which is also the default value:

( mb_language() );   // "neutral" (default if not set)
var_dump( mb_language( 'uni' ) );    // TRUE, valid language string
var_dump( mb_language() );    // "uni"
var_dump( mb_language( 'neutral' ) );    // TRUE, valid language string
var_dump( mb_language() );    // "neutral"
9 years ago
Note that you should better at least set "mbstring.internal_encoding".

Just check as below:


echo mb_internal_encoding() . '<br />';


You might be surprised at unexpected values.


mbstring.language Japanese
;mbstring.internal_encoding (commented out showing "no value" in phpinfo() )

These two lines in "php.ini" are the same values as


in Win / Linux servers.

"mbstring.internal_encoding" defines the default encoding for "mb_" Functions such as "mb_strlen()".

It also defines the same for "mb_ereg_" Functions such as "mb_ereg()" when you don't set "mb_regex_encoding".
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