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PHP Manual

## Runtime Configuration

The behaviour of these functions is affected by settings in php.ini.

mbstring configuration options
Name | Default | Changeable | Changelog
--- | --- | --- | ---
mbstring.language | "neutral" | PHP_INI_PERDIR | Available since PHP 4.3.0.
mbstring.detect_order | NULL | PHP_INI_ALL | Available since PHP 4.0.6.
mbstring.http_input | "pass" | PHP_INI_ALL | Available since PHP 4.0.6.
mbstring.http_output | "pass" | PHP_INI_ALL | Available since PHP 4.0.6.
mbstring.internal_encoding | NULL | PHP_INI_ALL | Available since PHP 4.0.6.
mbstring.script_encoding | NULL | PHP_INI_ALL | Available since PHP 4.3.0.
mbstring.substitute_character | NULL | PHP_INI_ALL | Available since PHP 4.0.6.
mbstring.func_overload | "0" | PHP_INI_PERDIR | PHP_INI_SYSTEM in PHP <= 4.2.3. Available since PHP 4.2.0.
mbstring.encoding_translation | "0" | PHP_INI_PERDIR | Available since PHP 4.3.0.
mbstring.strict_detection | "0" | PHP_INI_ALL | Available since PHP 5.1.2.

For the definition of the PHP_INI_* constants, please refer to ini_set().

Here's a short explanation of the configuration directives.

`mbstring.language` string

  The default national language setting (NLS) used in mbstring. Note that this option automagically defines mbstring.internal_encoding and mbstring.internal_encoding should be placed after mbstring.language in php.ini

`mbstring.encoding_translation` boolean

  Enables the transparent character encoding filter for the incoming HTTP queries, which performs detection and conversion of the input encoding to the internal character encoding.

`mbstring.internal_encoding` string

  Defines the default internal character encoding.

`mbstring.http_input` string

  Defines the default HTTP input character encoding.

`mbstring.http_output` string

  Defines the default HTTP output character encoding.

`mbstring.detect_order` string

  Defines default character code detection order. See also mb_detect_order().

`mbstring.substitute_character` string

  Defines character to substitute for invalid character encoding.

`mbstring.func_overload` string

  Overloads a set of single byte functions by the mbstring counterparts. See Function overloading for more information.

`mbstring.strict_detection` boolean

  Enables the strict encoding detection.

According to the » HTML 4.01 specification, Web browsers are allowed to encode a form being submitted with a character encoding different from the one used for the page. See mb_http_input() to detect character encoding used by browsers.

Although popular browsers are capable of giving a reasonably accurate guess to the character encoding of a given HTML document, it would be better to set the charset parameter in the Content-Type HTTP header to the appropriate value by header() or default_charset ini setting.

Example#1 php.ini setting examples

    ; Set default language
    mbstring.language        = Neutral; Set default language to Neutral(UTF-8) (default)
    mbstring.language        = English; Set default language to English
    mbstring.language        = Japanese; Set default language to Japanese

    ;; Set default internal encoding
    ;; Note: Make sure to use character encoding works with PHP
    mbstring.internal_encoding    = UTF-8  ; Set internal encoding to UTF-8

    ;; HTTP input encoding translation is enabled.
    mbstring.encoding_translation = On

    ;; Set default HTTP input character encoding
    ;; Note: Script cannot change http_input setting.
    mbstring.http_input           = pass    ; No conversion.
    mbstring.http_input           = auto    ; Set HTTP input to auto
                                    ; "auto" is expanded to "ASCII,JIS,UTF-8,EUC-JP,SJIS"
    mbstring.http_input           = SJIS    ; Set HTTP2 input to  SJIS
    mbstring.http_input           = UTF-8,SJIS,EUC-JP ; Specify order

    ;; Set default HTTP output character encoding
    mbstring.http_output          = pass    ; No conversion
    mbstring.http_output          = UTF-8   ; Set HTTP output encoding to UTF-8

    ;; Set default character encoding detection order
    mbstring.detect_order         = auto    ; Set detect order to auto
    mbstring.detect_order         = ASCII,JIS,UTF-8,SJIS,EUC-JP ; Specify order

    ;; Set default substitute character
    mbstring.substitute_character = 12307   ; Specify Unicode value
    mbstring.substitute_character = none    ; Do not print character
    mbstring.substitute_character = long    ; Long Example: U+3000,JIS+7E7E

Example#2 php.ini setting for EUC-JP users

    ;; Disable Output Buffering
    output_buffering      = Off

    ;; Set HTTP header charset
    default_charset       = EUC-JP

    ;; Set default language to Japanese
    mbstring.language = Japanese

    ;; HTTP input encoding translation is enabled.
    mbstring.encoding_translation = On

    ;; Set HTTP input encoding conversion to auto
    mbstring.http_input   = auto

    ;; Convert HTTP output to EUC-JP
    mbstring.http_output  = EUC-JP

    ;; Set internal encoding to EUC-JP
    mbstring.internal_encoding = EUC-JP

    ;; Do not print invalid characters
    mbstring.substitute_character = none

Example#3 php.ini setting for SJIS users

    ;; Enable Output Buffering
    output_buffering     = On

    ;; Set mb_output_handler to enable output conversion
    output_handler       = mb_output_handler

    ;; Set HTTP header charset
    default_charset      = Shift_JIS

    ;; Set default language to Japanese
    mbstring.language = Japanese

    ;; Set http input encoding conversion to auto
    mbstring.http_input  = auto

    ;; Convert to SJIS
    mbstring.http_output = SJIS

    ;; Set internal encoding to EUC-JP
    mbstring.internal_encoding = EUC-JP

    ;; Do not print invalid characters
    mbstring.substitute_character = none

Installation
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PHP Manual