LXII. iconv Functions

Introduction

This module contains an interface to iconv character set conversion facility. With this module, you can turn a string represented by a local character set into the one represented by another character set, which may be the Unicode character set. Supported character sets depend on the iconv implementation of your system. Note that the iconv function on some systems may not work as you expect. In such case, it'd be a good idea to install the GNU libiconv library. It will most likely end up with more consistent results.

Since PHP 5.0.0, this extension comes with various utility functions that help you to write multilingual scripts. Let's have a look at the following sections to explore the new features.

Requirements

You will need nothing if the system you are using is one of the recent POSIX-compliant systems because standard C libraries that are supplied in them must provide iconv facility. Otherwise, you have to get the libiconv library installed in your system.

Installation

To use functions provided by this module, the PHP binary must be built with the following configure line: --with-iconv[=DIR].

Note to Windows® Users: In order to enable this module on a Windows® environment, you need to put a DLL file named iconv.dll or iconv-1.3.dll (prior to 4.2.1) which is bundled with the PHP/Win32 binary package into a directory specified by the PATH environment variable or one of the system directories of your Windows® installation.

This module is part of PHP as of PHP 5 thus iconv.dll and php_iconv.dll is not needed anymore.

Runtime Configuration

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

Table 1. Iconv configuration options

NameDefaultChangeableChangelog
iconv.input_encoding"ISO-8859-1"PHP_INI_ALLAvailable since PHP 4.0.5.
iconv.output_encoding"ISO-8859-1"PHP_INI_ALLAvailable since PHP 4.0.5.
iconv.internal_encoding"ISO-8859-1"PHP_INI_ALLAvailable since PHP 4.0.5.
For further details and definitions of the PHP_INI_* constants, see the Appendix H.

Warning

Some systems (like IBM AIX) use "ISO8859-1" instead of "ISO-8859-1" so this value has to be used in configuration options and function parameters.

Note: Configuration option iconv.input_encoding is currently not used for anything.

Resource Types

This extension has no resource types defined.

Predefined Constants

Since PHP 4.3.0 it is possible to identify at runtime which iconv implementation is adopted by this extension.

Table 2. iconv constants

NameTypeDescription
ICONV_IMPLstringThe implementation name
ICONV_VERSIONstringThe implementation version

Note: Writing implementation-dependent scripts with these constants is strongly discouraged.

Since PHP 5.0.0, the following constants are also available:

Table 3. iconv constants available since PHP 5.0.0

NameTypeDescription
ICONV_MIME_DECODE_STRICTintegerA bitmask used for iconv_mime_decode()
ICONV_MIME_DECODE_CONTINUE_ON_ERRORintegerA bitmask used for iconv_mime_decode()

Table of Contents
iconv_get_encoding -- Retrieve internal configuration variables of iconv extension
iconv_mime_decode_headers -- Decodes multiple MIME header fields at once
iconv_mime_decode -- Decodes a MIME header field
iconv_mime_encode -- Composes a MIME header field
iconv_set_encoding -- Set current setting for character encoding conversion
iconv_strlen -- Returns the character count of string
iconv_strpos -- Finds position of first occurrence of a needle within a haystack
iconv_strrpos -- Finds the last occurrence of a needle within a haystack
iconv_substr -- Cut out part of a string
iconv -- Convert string to requested character encoding
ob_iconv_handler -- Convert character encoding as output buffer handler