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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