PHP
downloads | documentation | faq | getting help | mailing lists | reporting bugs | php.net sites | links | conferences | my php.net

search for in the

mb_check_encoding> <msql
Last updated: Sun, 25 Nov 2007

view this page in

Multibyte String Functions

Εισαγωγή

While there are many languages in which every necessary character can be represented by a one-to-one mapping to an 8-bit value, there are also several languages which require so many characters for written communication that they cannot be contained within the range a mere byte can code (A byte is made up of eight bits. Each bit can contain only two distinct values, one or zero. Because of this, a byte can only represent 256 unique values (two to the power of eight)). Multibyte character encoding schemes were developed to express more than 256 characters in the regular bytewise coding system.

When you manipulate (trim, split, splice, etc.) strings encoded in a multibyte encoding, you need to use special functions since two or more consecutive bytes may represent a single character in such encoding schemes. Otherwise, if you apply a non-multibyte-aware string function to the string, it probably fails to detect the beginning or ending of the multibyte character and ends up with a corrupted garbage string that most likely loses its original meaning.

mbstring provides multibyte specific string functions that help you deal with multibyte encodings in PHP. In addition to that, mbstring handles character encoding conversion between the possible encoding pairs. mbstring is designed to handle Unicode-based encodings such as UTF-8 and UCS-2 and many single-byte encodings for convenience (listed below).

PHP Character Encoding Requirements

Encodings of the following types are safely used with PHP.

  • A singlebyte encoding,

    • which has ASCII-compatible (ISO646 compatible) mappings for the characters in range of 00h to 7fh.

  • A multibyte encoding,

    • which has ASCII-compatible mappings for the characters in range of 00h to 7fh.
    • which don't use ISO2022 escape sequences.
    • which don't use a value from 00h to 7fh in any of the compounded bytes that represents a single character.

These are examples of character encodings that are unlikely to work with PHP. 

JIS, SJIS, ISO-2022-JP, BIG-5

Although PHP scripts written in any of those encodings might not work, especially in the case where encoded strings appear as identifiers or literals in the script, you can almost avoid using these encodings by setting up the mbstring's transparent encoding filter function for incoming HTTP queries.

Note: It's highly discouraged to use SJIS, BIG5, CP936, CP949 and GB18030 for the internal encoding unless you are familiar with the parser, the scanner and the character encoding.

Note: If you are connecting to a database with PHP, it is recommended that you use the same character encoding for both the database and the internal encoding for ease of use and better performance.
If you are using PostgreSQL, the character encoding used in the database and the one used in PHP may differ as it supports automatic character set conversion between the backend and the frontend.

Εγκατάσταση

mbstring is a non-default extension. This means it is not enabled by default. You must explicitly enable the module with the configure option. See the Install section for details.

The following configure options are related to the mbstring module.

  • --enable-mbstring: Enable mbstring functions. This option is required to use mbstring functions.

    libmbfl is necesarry for mbstring. libmbfl is bundled with mbstring. If libmbfl is already installed on the system, --with-libmbfl[=DIR] can be specified to use the installed library.

    As of PHP 4.3.0, mbstring extension provides enhanced support for Simplified Chinese, Traditional Chinese, Korean, and Russian in addition to Japanese.

    For PHP 4.3.3 or before, To enable that feature, you will have to supply either one of the following options to the LANG parameter of --enable-mbstring=LANG; --enable-mbstring=cn for Simplified Chinese support, --enable-mbstring=tw for Traditional Chinese support, --enable-mbstring=kr for Korean support, --enable-mbstring=ru for Russian support, and --enable-mbstring=ja for Japanese support (default). To enable all supported encoding, use --enable-mbstring=all.

    Note: As of PHP 4.3.4, all supported encoding by libmbfl is enabled with --enable-mbstring.

  • --enable-mbstr-enc-trans : Enable HTTP input character encoding conversion using mbstring conversion engine. If this feature is enabled, HTTP input character encoding may be converted to mbstring.internal_encoding automatically.

    Note: As of PHP 4.3.0, the option --enable-mbstr-enc-trans was eliminated and replaced with the runtime setting mbstring.encoding_translation. HTTP input character encoding conversion is enabled when this is set to On (the default is Off).

  • --disable-mbregex: Disable regular expression functions with multibyte character support.

Ρυθμίσεις κατά την εκτέλεση

Η συμπεριφορά αυτών των συναρτήσεων επιρεάζεται από τις ρυθμίσεις στο 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().

Ακολουθεί μια μικρή επεξήγηση των directive ρυθμίσεων.

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

Τύποι Πόρων

Αυτή η επέκταση δεν έχει resource τύπους ορισμένους.

Προκαθορισμένες Σταθερές

Οι σταθερές παρακάτω ορίζονται από αυτή την επέκταση, και θα είναι διαθέσιμες μόνο αν η επέκταση έχει γίνει compile μέσα στην PHP ή έχει φορτωθεί δυναμικά κατά την εκτέλεση.

MB_OVERLOAD_MAIL (integer)
MB_OVERLOAD_STRING (integer)
MB_OVERLOAD_REGEX (integer)
MB_CASE_UPPER (integer)
MB_CASE_LOWER (integer)
MB_CASE_TITLE (integer)

HTTP Input and Output

HTTP input/output character encoding conversion may convert binary data also. Users are supposed to control character encoding conversion if binary data is used for HTTP input/output.

Note: In PHP 4.3.2 or earlier versions, there was a limitation in this functionality that mbstring does not perform character encoding conversion in POST data if the enctype attribute in the form element is set to multipart/form-data. So you have to convert the incoming data by yourself in this case if necessary.
Beginning with PHP 4.3.3, if enctype for HTML form is set to multipart/form-data and mbstring.encoding_translation is set to On in php.ini the POST'ed variables and the names of uploaded files will be converted to the internal character encoding as well. However, the conversion isn't applied to the query keys.

  • HTTP Input

    There is no way to control HTTP input character conversion from a PHP script. To disable HTTP input character conversion, it has to be done in php.ini.

    Example#4 Disable HTTP input conversion in php.ini

    ;; Disable HTTP Input conversion
    mbstring.http_input = pass
    ;; Disable HTTP Input conversion (PHP 4.3.0 or higher)
    mbstring.encoding_translation = Off

    When using PHP as an Apache module, it is possible to override those settings in each Virtual Host directive in httpd.conf or per directory with .htaccess. Refer to the Configuration section and Apache Manual for details.

  • HTTP Output

    There are several ways to enable output character encoding conversion. One is using php.ini, another is using ob_start() with mb_output_handler() as the ob_start callback function.

    Note: PHP3-i18n users should note that mbstring's output conversion differs from PHP3-i18n. Character encoding is converted using an output buffer.

Example#5 php.ini setting example

;; Enable output character encoding conversion for all PHP pages

;; Enable Output Buffering
output_buffering    = On

;; Set mb_output_handler to enable output conversion
output_handler      = mb_output_handler

Example#6 Script example

<?php

// Enable output character encoding conversion only for this page

// Set HTTP output character encoding to SJIS
mb_http_output('SJIS');

// Start buffering and specify "mb_output_handler" as
// callback function
ob_start('mb_output_handler');

?>

Supported Character Encodings

Currently the following character encodings are supported by the mbstring module. Any of those Character encodings can be specified in the encoding parameter of mbstring functions.

The following character encodings are supported in this PHP extension:

  • UCS-4
  • UCS-4BE
  • UCS-4LE
  • UCS-2
  • UCS-2BE
  • UCS-2LE
  • UTF-32
  • UTF-32BE
  • UTF-32LE
  • UTF-16
  • UTF-16BE
  • UTF-16LE
  • UTF-7
  • UTF7-IMAP
  • UTF-8
  • ASCII
  • EUC-JP
  • SJIS
  • eucJP-win
  • SJIS-win
  • ISO-2022-JP
  • JIS
  • ISO-8859-1
  • ISO-8859-2
  • ISO-8859-3
  • ISO-8859-4
  • ISO-8859-5
  • ISO-8859-6
  • ISO-8859-7
  • ISO-8859-8
  • ISO-8859-9
  • ISO-8859-10
  • ISO-8859-13
  • ISO-8859-14
  • ISO-8859-15
  • byte2be
  • byte2le
  • byte4be
  • byte4le
  • BASE64
  • HTML-ENTITIES
  • 7bit
  • 8bit
  • EUC-CN
  • CP936
  • HZ
  • EUC-TW
  • CP950
  • BIG-5
  • EUC-KR
  • UHC (CP949)
  • ISO-2022-KR
  • Windows-1251 (CP1251)
  • Windows-1252 (CP1252)
  • CP866 (IBM866)
  • KOI8-R

Any php.ini entry which accepts an encoding name can also use the values "auto" and "pass". mbstring functions which accept an encoding name can also use the value "auto".

If "pass" is set, no character encoding conversion is performed.

If "auto" is set, it is expanded to the list of encodings defined per the NLS. For instance, if the NLS is set to Japanese, the value is assumed to be "ASCII,JIS,UTF-8,EUC-JP,SJIS".

See also mb_detect_order()

Function Overloading Feature

You might often find it difficult to get an existing PHP application to work in a given multibyte environment. This happens because most PHP applications out there are written with the standard string functions such as substr(), which are known to not properly handle multibyte-encoded strings.

mbstring supports a 'function overloading' feature which enables you to add multibyte awareness to such an application without code modification by overloading multibyte counterparts on the standard string functions. For example, mb_substr() is called instead of substr() if function overloading is enabled. This feature makes it easy to port applications that only support single-byte encodings to a multibyte environment in many cases.

To use function overloading, set mbstring.func_overload in php.ini to a positive value that represents a combination of bitmasks specifying the categories of functions to be overloaded. It should be set to 1 to overload the mail() function. 2 for string functions, 4 for regular expression functions. For example, if it is set to 7, mail, strings and regular expression functions will be overloaded. The list of overloaded functions are shown below.

Functions to be overloaded
value of mbstring.func_overload original function overloaded function
1 mail() mb_send_mail()
2 strlen() mb_strlen()
2 strpos() mb_strpos()
2 strrpos() mb_strrpos()
2 substr() mb_substr()
2 strtolower() mb_strtolower()
2 strtoupper() mb_strtoupper()
2 substr_count() mb_substr_count()
4 ereg() mb_ereg()
4 eregi() mb_eregi()
4 ereg_replace() mb_ereg_replace()
4 eregi_replace() mb_eregi_replace()
4 split() mb_split()

Note: It is not recommended to use the function overloading option in the per-directory context, because it's not confirmed yet to be stable enough in a production environment and may lead to undefined behaviour.

Basics of Japanese multi-byte encodings

Japanese characters can only be represented by multibyte encodings, and multiple encoding standards are used depending on platform and text purpose. To make matters worse, these encoding standards differ slightly from one another. In order to create a web application which would be usable in a Japanese environment, a developer has to keep these complexities in mind to ensure that the proper character encodings are used.

  • Storage for a character can be up to six bytes
  • Most Japanese multibyte characters appear twice as wide as single-byte characters. These characters are called "zen-kaku" in Japanese, which means "full width". Other, narrower, characters are called "han-kaku", which means "half width". The graphical properties of the characters, however, depends upon the type faces used to display them.
  • Some character encodings use shift(escape) sequences defined in ISO-2022 to switch the code map of the specific code area (00h to 7fh).
  • ISO-2022-JP should be used in SMTP/NNTP, and headers and entities should be reencoded as per RFC requirements. Although those are not requisites, it's still a good idea because several popular user agents cannot recognize any other encoding methods.
  • Web pages created for mobile phone services such as » i-mode, » Vodafone live!, or » EZweb are supposed to use Shift_JIS.

References

Multibyte character encoding schemes and their related issues are fairly complicated, and are beyond the scope of this documentation. Please refer to the following URLs and other resources for further information regarding these topics.

Summaries of supported encodings

Summaries of supported encodings
Name in the IANA character set registry:ISO-10646-UCS-4
Underlying character set:ISO 10646
Description: The Universal Character Set with 31-bit code space, standardized as UCS-4 by ISO/IEC 10646. It is kept synchronized with the latest version of the Unicode code map.
Additional note: If this name is used in the encoding conversion facility, the converter attempts to identify by the preceding BOM (byte order mark)in which endian the subsequent bytes are represented.
Name in the IANA character set registry:ISO-10646-UCS-4
Underlying character set:UCS-4
Description: See above.
Additional note: In contrast to UCS-4, strings are always assumed to be in big endian form.
Name in the IANA character set registry:ISO-10646-UCS-4
Underlying character set:UCS-4
Description: See above.
Additional note: In contrast to UCS-4, strings are always assumed to be in little endian form.
Name in the IANA character set registry:ISO-10646-UCS-2
Underlying character set:UCS-2
Description: The Universal Character Set with 16-bit code space, standardized as UCS-2 by ISO/IEC 10646. It is kept synchronized with the latest version of the unicode code map.
Additional note: If this name is used in the encoding conversion facility, the converter attempts to identify by the preceding BOM (byte order mark)in which endian the subsequent bytes are represented.
Name in the IANA character set registry:ISO-10646-UCS-2
Underlying character set:UCS-2
Description: See above.
Additional note: In contrast to UCS-2, strings are always assumed to be in big endian form.
Name in the IANA character set registry:ISO-10646-UCS-2
Underlying character set:UCS-2
Description: See above.
Additional note: In contrast to UCS-2, strings are always assumed to be in little endian form.
Name in the IANA character set registry:UTF-32
Underlying character set:Unicode
Description: Unicode Transformation Format of 32-bit unit width, whose encoding space refers to the Unicode's codeset standard. This encoding scheme wasn't identical to UCS-4 because the code space of Unicode were limited to a 21-bit value.
Additional note: If this name is used in the encoding conversion facility, the converter attempts to identify by the preceding BOM (byte order mark)in which endian the subsequent bytes are represented.
Name in the IANA character set registry:UTF-32BE
Underlying character set:Unicode
Description:See above
Additional note: In contrast to UTF-32, strings are always assumed to be in big endian form.
Name in the IANA character set registry:UTF-32LE
Underlying character set:Unicode
Description:See above
Additional note: In contrast to UTF-32, strings are always assumed to be in little endian form.
Name in the IANA character set registry:UTF-16
Underlying character set:Unicode
Description: Unicode Transformation Format of 16-bit unit width. It's worth a note that UTF-16 is no longer the same specification as UCS-2 because the surrogate mechanism has been introduced since Unicode 2.0 and UTF-16 now refers to a 21-bit code space.
Additional note: If this name is used in the encoding conversion facility, the converter attempts to identify by the preceding BOM (byte order mark)in which endian the subsequent bytes are represented.
Name in the IANA character set registry:UTF-16BE
Underlying character set:Unicode
Description: See above.
Additional note: In contrast to UTF-16, strings are always assumed to be in big endian form.
Name in the IANA character set registry:UTF-16LE
Underlying character set:Unicode
Description: See above.
Additional note: In contrast to UTF-16, strings are always assumed to be in little endian form.
Name in the IANA character set registry:UTF-8
Underlying character set:Unicode / UCS
Description: Unicode Transformation Format of 8-bit unit width.
Additional note:none
Name in the IANA character set registry:UTF-7
Underlying character set:Unicode
Description: A mail-safe transformation format of Unicode, specified in » RFC2152.
Additional note:none
Name in the IANA character set registry:(none)
Underlying character set:Unicode
Description: A variant of UTF-7 which is specialized for use in the » IMAP protocol.
Additional note:none
Name in the IANA character set registry: US-ASCII (preferred MIME name) / iso-ir-6 / ANSI_X3.4-1986 / ISO_646.irv:1991 / ASCII / ISO646-US / us / IBM367 / CP367 / csASCII
Underlying character set:ASCII / ISO 646
Description: American Standard Code for Information Interchange is a commonly-used 7-bit encoding. Also standardized as an international standard, ISO 646.
Additional note:(none)
Name in the IANA character set registry: EUC-JP (preferred MIME name) / Extended_UNIX_Code_Packed_Format_for_Japanese / csEUCPkdFmtJapanese
Underlying character set: Compound of US-ASCII / JIS X0201:1997 (hankaku kana part) / JIS X0208:1990 / JIS X0212:1990
Description: As you see the name is derived from an abbreviation of Extended UNIX Code Packed Format for Japanese, this encoding is mostly used on UNIX or alike platforms. The original encoding scheme, Extended UNIX Code, is designed on the basis of ISO 2022.
Additional note: The character set referred to by EUC-JP is different to IBM932 / CP932, which are used by OS/2® and Microsoft® Windows®. For information interchange with those platforms, use EUCJP-WIN instead.
Name in the IANA character set registry:Shift_JIS (preferred MIME name) / MS_Kanji / csShift_JIS
Underlying character set:Compound of JIS X0201:1997 / JIS X0208:1997
Description: Shift_JIS was developed in early 80's, at the time personal Japanese word processors were brought into the market, in order to maintain compatiblities with the legacy encoding scheme JIS X 0201:1976. According to the IANA definition the codeset of Shift_JIS is slightly different to IBM932 / CP932. However, the names "SJIS" / "Shift_JIS" are often wrongly used to refer to these codesets.
Additional note:For the CP932 codemap, use SJIS-WIN instead.
Name in the IANA character set registry:(none)
Underlying character set: Compound of JIS X0201:1997 / JIS X0208:1997 / IBM extensions / NEC extensions
Description: While this "encoding" uses the same encoding scheme as EUC-JP, the underlying character set is different. That is, some code points map to different characters than EUC-JP.
Additional note:none
Name in the IANA character set registry:Windows-31J / csWindows31J
Underlying character set: Compound of JIS X0201:1997 / JIS X0208:1997 / IBM extensions / NEC extensions
Description: While this "encoding" uses the same encoding scheme as Shift_JIS, the underlying character set is different. That means some code points map to different characters than Shift_JIS.
Additional note:(none)
Name in the IANA character set registry:ISO-2022-JP (preferred MIME name) / csISO2022JP
Underlying character set: US-ASCII / JIS X0201:1976 / JIS X0208:1978 / JIS X0208:1983
Description:» RFC1468
Additional note:(none)
Name in the IANA character set registry:JIS
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:ISO-8859-1
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:ISO-8859-2
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:ISO-8859-3
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:ISO-8859-4
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:ISO-8859-5
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:ISO-8859-6
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:ISO-8859-7
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:ISO-8859-8
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:ISO-8859-9
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:ISO-8859-10
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:ISO-8859-13
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:ISO-8859-14
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:ISO-8859-15
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:byte2be
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:byte2le
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:byte4be
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:byte4le
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:BASE64
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:HTML-ENTITIES
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:7bit
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:8bit
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:EUC-CN
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:CP936
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:HZ
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:EUC-TW
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:CP950
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:BIG-5
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:EUC-KR
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:UHC (CP949)
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:ISO-2022-KR
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:Windows-1251 (CP1251)
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:Windows-1252 (CP1252)
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:CP866 (IBM866)
Underlying character set:
Description:
Additional note:
Name in the IANA character set registry:KOI8-R
Underlying character set:
Description:
Additional note:

Table of Contents



mb_check_encoding> <msql
Last updated: Sun, 25 Nov 2007
 
add a note add a note User Contributed Notes
Multibyte String
marc at ermshaus dot org
03-Oct-2008 03:05
A small correction to patrick at hexane dot org's mb_str_replace function. The original function does not work as intended in case $replacement contains $needle.

<?php
function mb_str_replace($needle, $replacement, $haystack)
{
    $needle_len = mb_strlen($needle);
    $replacement_len = mb_strlen($replacement);
    $pos = mb_strpos($haystack, $needle);
    while ($pos !== false)
    {
        $haystack = mb_substr($haystack, 0, $pos) . $replacement
                . mb_substr($haystack, $pos + $needle_len);
        $pos = mb_strpos($haystack, $needle, $pos + $replacement_len);
    }
    return $haystack;
}
?>
patrick at hexane dot org
27-Jun-2008 08:18
I wonder why there isn't a mb_str_replace().  Here's one for now:

function mb_str_replace( $needle, $replacement, $haystack ) {
  $needle_len = mb_strlen($needle);
  $pos = mb_strpos( $haystack, $needle);
  while (!($pos ===false)) {
    $front = mb_substr( $haystack, 0, $pos );
    $back  = mb_substr( $haystack, $pos + $needle_len);
    $haystack = $front.$replacement.$back;
    $pos = mb_strpos( $haystack, $needle);
  }
  return $haystack;
}
tonyboyd
17-Oct-2007 11:52
JOECOLE, isn't this the same thing?

$str = mb_convert_case($str, MB_CASE_TITLE, "UTF-8");
Smelly
25-Apr-2007 10:09
Below is some code to output a UTF-8 encoded CSV in a way understandable by Excel. It requires iconv instead of mbstring.

header("Content-type: application/octet-stream");
header("Content-Transfer-Encoding: binary");
header("Content-Disposition: attachment; filename=report.xls");
   
// assume $tmpString contains UTF-8 encoded CSV:
$tmpString =  iconv ( 'UTF-8', 'UTF-16LE//IGNORE', $tmpString );

print chr(255).chr(254).$tmpString;
chris at maedata dot com
24-Apr-2007 09:50
The opposite of what Eugene Murai wrote in a previous comment is true when importing/uploading a file. For instance, if you export an Excel spreadsheet using the Save As Unicode Text option, you can use the following to convert it to UTF-8 after uploading:

//Convert file to UTF-8 in case Windows mucked it up
$file = explode( "\n", mb_convert_encoding( trim( file_get_contents( $_FILES['file']['tmp_name'] ) ), 'UTF-8', 'UTF-16' ) );
mdoocy at u dot washington dot edu
14-Mar-2007 11:30
Note that some of the multi-byte functions run in O(n) time, rather than constant time as is the case for their single-byte equivalents. This includes any functionality requiring access at a specific index, since random access is not possible in a string whose number of bytes will not necessarily match the number of characters. Affected functions include: mb_substr(), mb_strstr(), mb_strcut(), mb_strpos(), etc.
motin at demomusic dot nu
16-Feb-2007 05:24
Follow up on last note from 2007-jan-20: http://se2.php.net/manual/en/function.mb-strlen.php#72979

There is the correct way of simulating singlebyte strlen as well as some pitfalls to watch out for when developing in a mb-func_overload:ed environment.
motin at demomusic dot nu
19-Jan-2007 05:12
As peter dot albertsson at spray dot se already pointed out, overloading strlen may break code that handles binary data and relies upon strlen for bytelengths.

The problem occurs when a file is filled with a string using fwrite in the following manner:

$len = strlen($data);
fwrite($fp, $data, $len);

fwrite takes amount of bytes as the third parameter, but mb_strlen returns the amount of characters in the string. Since multibyte characters are possibly more than one byte in length each - this will result in that the last characters of $data never gets written to the file.

After hours of investigating why PEAR::Cache_Lite didn't work - the above is what I found.

I made an attempt at using single byte functions, but it doesn't work. Posting here anyway in case it helps someone else:

/**
* PHP Singe byte functions simulation (non successful)
*
* Usage: sb_string(functionname, arg1, arg2, etc);
* Example: sb_string("strlen", "tuöéä"); returns 8 (should...)
*/
function sb_string() {

  $arguments = func_get_args();

  $func_overloading = ini_get("mbstring.func_overload");

  ini_set("mbstring.func_overload", 0);

  $ret = call_user_func_array(array_shift($arguments), $arguments);

  ini_set("mbstring.func_overload", $func_overloading);

  return $ret;

}
pdezwart .at. snocap
10-Oct-2006 11:28
If you are trying to emulate the UnicodeEncoding.Unicode.GetBytes() function in .NET, the encoding you want to use is: UCS-2LE
hayk at mail dot ru
17-Aug-2006 12:36
Since PHP 5.1.0 and PHP 4.4.2 there is an Armenian ArmSCII-8 (ArmSCII-8, ArmSCII8, ARMSCII-8, ARMSCII8) encoding avaliable.
daniel at softel dot jp
24-Jul-2006 04:41
Note that although "multi-byte" hints at total internationalization, the mb_ API was designed by a Japanese person to support the Japanese language.

Some of the functions, for example mb_convert_kana(), make absolutely no sense outside of a Japanese language environment.

It should perhaps be considered "lucky" if the functions work with non-Japanese multi-byte languages.

I don't mean any disrespect to the mb_ API because I'm using it everyday and I appreciate its usefulness, but maybe a better name would be the jp_ API.
Aardvark
13-Mar-2006 11:37
Since not all hosted servces currently support the multi-byte function set, it may still be necessary to process Unicode strings using standard single byte functions.  The function at the following link - http://www.kanolife.com/escape/2006/03/php-unicode-processing.html - shows by example how to do this.  While this only covers UTF-8, the standard PHP function "iconv" allows conversion into and out of UTF-8 if strings need to be input or output in other encodings.
peter kehl
09-Mar-2006 08:34
UTF-16LE solution for CSV for Excel by Eugene Murai works well:
$unicode_str_for_Excel = chr(255).chr(254).mb_convert_encoding( $utf8_str, 'UTF-16LE', 'UTF-8');

However, then Excel on Mac OS X doesn't identify columns properly and its puts each whole row in its own cell. In order to fix that, use TAB "\\t" character as CSV delimiter rather than comma or colon.

You may also want to use HTTP encoding header, such as
header( "Content-type: application/vnd.ms-excel; charset=UTF-16LE" );
14-Aug-2005 07:24
get the string octet-size, when mbstring.func_overload is set to 2 :

<?php
function str_sizeof($string) {
    return count(preg_split("`.`", $string)) - 1 ;
}
?>

answering to peter albertsson, once you got your data octet-size, you can access each octet with something
$string[0] ... $string[$size-1], since the [ operator doesn't complies with multibytes strings.
peter dot albertsson at spray dot se
21-May-2005 03:43
Setting mbstring.func_overload = 2 may break your applications that deal with binary data.

After having set mbstring.func_overload = 2 and  mbstring.internal_encoding = UTF-8 I can't even read a binary file and print/echo it to output without corrupting it.
nzkiwi at NOSPAMmte dot biglobe dot ne dot jp
13-Apr-2005 04:37
A friend has pointed out that the entry
"mbstring.http_input PHP_INI_ALL" in Table 1 on the mbstring page appears to be wrong: above Example 4 it says that "There is no way to control HTTP input character conversion from PHP script. To disable HTTP input character conversion, it has to be done in php.ini".
Also the table shows the old-PHP-version defaults:
;; Disable HTTP Input conversion
mbstring.http_input = pass  *BUT* (for PHP 4.3.0 or higher)
;; Disable HTTP Input conversion
mbstring.encoding_translation = Off
Eugene Murai
23-Feb-2005 10:20
PHP can input and output Unicode, but a little different from what Microsoft means: when Microsoft says "Unicode", it unexplicitly means little-endian UTF-16 with BOM(FF FE = chr(255).chr(254)), whereas PHP's "UTF-16" means big-endian with BOM. For this reason, PHP does not seem to be able to output Unicode CSV file for Microsoft Excel. Solving this problem is quite simple: just put BOM infront of UTF-16LE string.

Example:

$unicode_str_for_Excel = chr(255).chr(254).mb_convert_encoding( $utf8_str, 'UTF-16LE', 'UTF-8');
Geoffrey
01-Feb-2005 12:59
For Windows users php_mbstring can be added as follows:-

if you have dowloaded  the "short" version of PHP,
(php-4.3.10-installer.exe), download the full version .
(php-4.3.10-Win32.zip)

unzip it, find php_mbstring.dll in
f:\php-4.3.10-Win32\extensions, and copy it across to your
php\extensions directory

use Notepad to open your PHP.INI

change the extension_dir line to read
extension_dir = "e:\php\extensions\"  (or whatever your
directory is called)

remove the semi-colon on line
 ; extension=php_mbstring.dll

save PHP.INI,  restart PHP
add a note add a note

mb_check_encoding> <msql
Last updated: Sun, 25 Nov 2007