## Runtime Configuration

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

mbstring configuration options
Name | Default | Changeable | Changelog
--- | --- | --- | ---
mbstring.language | "neutral" | `INI_ALL` |
mbstring.detect_order | NULL | `INI_ALL` |
mbstring.http_input | "pass" | `INI_ALL` | Deprecated
mbstring.http_output | "pass" | `INI_ALL` | Deprecated
mbstring.internal_encoding | NULL | `INI_ALL` | Deprecated
mbstring.substitute_character | NULL | `INI_ALL` |
mbstring.func_overload | "0" | `INI_SYSTEM` | Deprecated as of PHP 7.2.0; removed as of PHP 8.0.0.
mbstring.encoding_translation | "0" | `INI_PERDIR` |
mbstring.http_output_conv_mimetypes | "^(text/|application/xhtml\+xml)" | `INI_ALL` |
mbstring.strict_detection | "0" | `INI_ALL` |
mbstring.regex_retry_limit | "1000000" | `INI_ALL` | Available as of PHP 7.4.0.
mbstring.regex_stack_limit | "100000" | `INI_ALL` | Available as of PHP 7.3.5.

For further details and definitions of the 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

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