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  
mbstring.detect_order NULL PHP_INI_ALL  
mbstring.http_input "pass" PHP_INI_ALL Deprecated
mbstring.http_output "pass" PHP_INI_ALL Deprecated
mbstring.internal_encoding NULL PHP_INI_ALL Deprecated
mbstring.substitute_character NULL PHP_INI_ALL  
mbstring.func_overload "0" PHP_INI_SYSTEM Deprecated as of PHP 7.2.0; removed as of PHP 8.0.0.
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 Available as of PHP 7.4.0.
mbstring.regex_stack_limit "100000" PHP_INI_ALL Available as of PHP 7.3.5.
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 bool

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
Warning

This deprecated feature will certainly be removed in the future.

Defines the default internal character encoding.

Users should leave this empty and set default_charset instead.

mbstring.http_input string
Warning

This deprecated feature will certainly be removed in the future.

Defines the default HTTP input character encoding.

Users should leave this empty and set default_charset instead.

mbstring.http_output string
Warning

This deprecated feature will certainly be removed in the future.

Defines the default HTTP output character encoding (output will be converted from the internal encoding to the HTTP output encoding upon output).

Users should leave this empty and set default_charset instead.

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. See mb_substitute_character() for supported values.

mbstring.func_overload string
Warning

This feature has been DEPRECATED as of PHP 7.2.0, and REMOVED as of PHP 8.0.0. Relying on this feature is highly discouraged.

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

This setting can only be changed from the php.ini file.

mbstring.http_output_conv_mimetypes string

mbstring.strict_detection bool

Enables strict encoding detection. See mb_detect_encoding() for a description and examples.

mbstring.regex_retry_limit int

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

This setting only takes effect when linking against oniguruma >= 6.8.0.

mbstring.regex_stack_limit int

Limits the stack depth of mbstring regular expressions.

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