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_ALL	Available since PHP 4.3.0.; PHP_INI_PERDIR in PHP <= 5.2.6
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_SYSTEM	PHP_INI_SYSTEM in PHP <= 4.2.3; PHP_INI_SYSTEM \| PHP_INI_PERDIR from PHP 4.3 through 5.2.6. 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 further details and definitions of the PHP_INI_* modes, see the Where a configuration setting may be 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 according to mbstring.language
mbstring.http_input           = SJIS    ; Set HTTP 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