Character Set Conversion
<!-- ##### SECTION Short_Description ##### -->
-convert strings between different character sets using iconv()
-<!-- ##### SECTION Long_Description ##### -->
-<para>
-</para>
+<!-- ##### SECTION Long_Description ##### -->
- <refsect2 id="file-name-encodings">
- <title>File Name Encodings</title>
-
- <para>
- Historically, Unix has not had a defined encoding for file
- names: a file name is valid as long as it does not have path
- separators in it ("/"). However, displaying file names may
- require conversion: from the character set in which they were
- created, to the character set in which the application
- operates. Consider the Spanish file name
- "<filename>Presentación.sxi</filename>". If the
- application which created it uses ISO-8859-1 for its encoding,
- then the actual file name on disk would look like this:
- </para>
-
- <programlisting id="filename-iso8859-1">
-Character: P r e s e n t a c i ó n . s x i
-Hex code: 50 72 65 73 65 6e 74 61 63 69 f3 6e 2e 73 78 69
- </programlisting>
-
- <para>
- However, if the application use UTF-8, the actual file name on
- disk would look like this:
- </para>
-
- <programlisting id="filename-utf-8">
-Character: P r e s e n t a c i ó n . s x i
-Hex code: 50 72 65 73 65 6e 74 61 63 69 c3 b3 6e 2e 73 78 69
- </programlisting>
-
- <para>
- Glib uses UTF-8 for its strings, and GUI toolkits like GTK+
- that use Glib do the same thing. If you get a file name from
- the file system, for example, from
- <function>readdir(3)</function> or from <link
- linkend="g_dir_read_name"><function>g_dir_read_name()</function></link>,
- and you wish to display the file name to the user, you
- <emphasis>will</emphasis> need to convert it into UTF-8. The
- opposite case is when the user types the name of a file he
- wishes to save: the toolkit will give you that string in
- UTF-8 encoding, and you will need to convert it to the
- character set used for file names before you can create the
- file with <function>open(2)</function> or
- <function>fopen(3)</function>.
- </para>
-
- <para>
- By default, Glib assumes that file names on disk are in UTF-8
- encoding. This is a valid assumption for file systems which
- were created relatively recently: most applications use UTF-8
- encoding for their strings, and that is also what they use for
- the file names they create. However, older file systems may
- still contain file names created in "older" encodings, such as
- ISO-8859-1. In this case, for compatibility reasons, you may
- want to instruct Glib to use that particular encoding for file
- names rather than UTF-8. You can do this by specifying the
- encoding for file names in the <link
- linkend="G_FILENAME_ENCODING"><envar>G_FILENAME_ENCODING</envar></link>
- environment variable. For example, if your installation uses
- ISO-8859-1 for file names, you can put this in your
- <filename>~/.profile</filename>:
- </para>
-
- <programlisting>
-export G_FILENAME_ENCODING=ISO-8859-1
- </programlisting>
-
- <para>
- Glib provides the functions <link
- linkend="g_filename_to_utf8"><function>g_filename_to_utf8()</function></link>
- and <link
- linkend="g_filename_from_utf8"><function>g_filename_from_utf8()</function></link>
- to perform the necessary conversions. These functions convert
- file names from the encoding specified in
- <envar>G_FILENAME_ENCODING</envar> to UTF-8 and vice-versa.
- <xref linkend="file-name-encodings-diagram"/> illustrates how
- these functions are used to convert between UTF-8 and the
- encoding for file names in the file system.
- </para>
-
- <figure id="file-name-encodings-diagram">
- <title>Conversion between File Name Encodings</title>
- <graphic fileref="file-name-encodings.png" format="PNG"/>
- </figure>
-
- <refsect3 id="file-name-encodings-checklist">
- <title>Checklist for Application Writers</title>
-
- <para>
- This section is a practical summary of the detailed
- description above. You can use this as a checklist of
- things to do to make sure your applications process file
- name encodings correctly.
- </para>
-
- <orderedlist>
- <listitem>
- <para>
- If you get a file name from the file system from a
- function such as <function>readdir(3)</function> or
- <function>gtk_file_chooser_get_filename()</function>,
- you do not need to do any conversion to pass that
- file name to functions like <function>open(2)</function>,
- <function>rename(2)</function>, or
- <function>fopen(3)</function> — those are "raw"
- file names which the file system understands.
- </para>
- </listitem>
-
- <listitem>
- <para>
- If you need to display a file name, convert it to UTF-8
- first by using <link
- linkend="g_filename_to_utf8"><function>g_filename_to_utf8()</function></link>.
- If conversion fails, display a string like
- "<literal>Unknown file name</literal>". <emphasis>Do
- not</emphasis> convert this string back into the
- encoding used for file names if you wish to pass it to
- the file system; use the original file name instead.
- For example, the document window of a word processor
- could display "Unknown file name" in its title bar but
- still let the user save the file, as it would keep the
- raw file name internally. This can happen if the user
- has not set the <envar>G_FILENAME_ENCODING</envar>
- environment variable even though he has files whose
- names are not encoded in UTF-8.
- </para>
- </listitem>
-
- <listitem>
- <para>
- If your user interface lets the user type a file name
- for saving or renaming, convert it to the encoding used
- for file names in the file system by using <link
- linkend="g_filename_from_utf8"><function>g_filename_from_utf8()</function></link>.
- Pass the converted file name to functions like
- <function>fopen(3)</function>. If conversion fails, ask
- the user to enter a different file name. This can
- happen if the user types Japanese characters when
- <envar>G_FILENAME_ENCODING</envar> is set to
- <literal>ISO-8859-1</literal>, for example.
- </para>
- </listitem>
- </orderedlist>
- </refsect3>
- </refsect2>
<!-- ##### SECTION See_Also ##### -->
<para>
<!-- ##### STRUCT GIConv ##### -->
<para>
-The <structname>GIConv</structname> struct wraps an
-<function>iconv()</function> conversion descriptor. It contains private data
-and should only be accessed using the following functions.
+
</para>
<!-- ##### MACRO G_CONVERT_ERROR ##### -->
<para>
-Error domain for character set conversions. Errors in this domain will
-be from the #GConvertError enumeration. See #GError for information on
-error domains.
+
</para>
<!-- ##### ENUM GConvertError ##### -->
<para>
-Error codes returned by character set conversion routines.
+
</para>
-@G_CONVERT_ERROR_NO_CONVERSION: Conversion between the requested character sets
-is not supported.
-@G_CONVERT_ERROR_ILLEGAL_SEQUENCE: Invalid byte sequence in conversion input.
-@G_CONVERT_ERROR_FAILED: Conversion failed for some reason.
-@G_CONVERT_ERROR_PARTIAL_INPUT: Partial character sequence at end of input.
-@G_CONVERT_ERROR_BAD_URI: URI is invalid.
-@G_CONVERT_ERROR_NOT_ABSOLUTE_PATH: Pathname is not an absolute path.
+@G_CONVERT_ERROR_NO_CONVERSION:
+@G_CONVERT_ERROR_ILLEGAL_SEQUENCE:
+@G_CONVERT_ERROR_FAILED:
+@G_CONVERT_ERROR_PARTIAL_INPUT:
+@G_CONVERT_ERROR_BAD_URI:
+@G_CONVERT_ERROR_NOT_ABSOLUTE_PATH:
<!-- ##### FUNCTION g_get_charset ##### -->
<para>
#endif
+/**
+ * SECTION:conversions
+ * @title: Character Set Conversion
+ * @short_description: Convert strings between different character sets
+ *
+ * The g_convert() family of function wraps the functionality of iconv(). In
+ * addition to pure character set conversions, GLib has functions to deal
+ * with the extra complications of encodings for file names.
+ *
+ * <refsect2 id="file-name-encodings">
+ * <title>File Name Encodings</title>
+ * <para>
+ * Historically, Unix has not had a defined encoding for file
+ * names: a file name is valid as long as it does not have path
+ * separators in it ("/"). However, displaying file names may
+ * require conversion: from the character set in which they were
+ * created, to the character set in which the application
+ * operates. Consider the Spanish file name
+ * "<filename>Presentación.sxi</filename>". If the
+ * application which created it uses ISO-8859-1 for its encoding,
+ * </para>
+ * <programlisting id="filename-iso8859-1">
+ * Character: P r e s e n t a c i ó n . s x i
+ * Hex code: 50 72 65 73 65 6e 74 61 63 69 f3 6e 2e 73 78 69
+ * </programlisting>
+ * <para>
+ * However, if the application use UTF-8, the actual file name on
+ * disk would look like this:
+ * </para>
+ * <programlisting id="filename-utf-8">
+ * Character: P r e s e n t a c i ó n . s x i
+ * Hex code: 50 72 65 73 65 6e 74 61 63 69 c3 b3 6e 2e 73 78 69
+ * </programlisting>
+ * <para>
+ * Glib uses UTF-8 for its strings, and GUI toolkits like GTK+
+ * that use Glib do the same thing. If you get a file name from
+ * the file system, for example, from readdir(3) or from g_dir_read_name(),
+ * and you wish to display the file name to the user, you
+ * emphasis>will</emphasis> need to convert it into UTF-8. The
+ * opposite case is when the user types the name of a file he
+ * wishes to save: the toolkit will give you that string in
+ * UTF-8 encoding, and you will need to convert it to the
+ * character set used for file names before you can create the
+ * file with open(2) or fopen(3).
+ * </para>
+ * <para>
+ * By default, Glib assumes that file names on disk are in UTF-8
+ * encoding. This is a valid assumption for file systems which
+ * were created relatively recently: most applications use UTF-8
+ * encoding for their strings, and that is also what they use for
+ * the file names they create. However, older file systems may
+ * still contain file names created in "older" encodings, such as
+ * ISO-8859-1. In this case, for compatibility reasons, you may
+ * want to instruct Glib to use that particular encoding for file
+ * names rather than UTF-8. You can do this by specifying the
+ * encoding for file names in the <link
+ * linkend="G_FILENAME_ENCODING"><envar>G_FILENAME_ENCODING</envar></link>
+ * environment variable. For example, if your installation uses
+ * ISO-8859-1 for file names, you can put this in your
+ * <filename>~/.profile</filename>:
+ * </para>
+ * <programlisting>
+ * export G_FILENAME_ENCODING=ISO-8859-1
+ * </programlisting>
+ * <para>
+ * Glib provides the functions g_filename_to_utf8() and
+ * g_filename_from_utf8() to perform the necessary conversions. These
+ * functions convert file names from the encoding specified in
+ * <envar>G_FILENAME_ENCODING</envar> to UTF-8 and vice-versa.
+ * <xref linkend="file-name-encodings-diagram"/> illustrates how
+ * these functions are used to convert between UTF-8 and the
+ * encoding for file names in the file system.
+ * </para>
+ * <figure id="file-name-encodings-diagram">
+ * <title>Conversion between File Name Encodings</title>
+ * <graphic fileref="file-name-encodings.png" format="PNG"/>
+ * </figure>
+ * <refsect3 id="file-name-encodings-checklist">
+ * <title>Checklist for Application Writers</title>
+ * <para>
+ * This section is a practical summary of the detailed
+ * description above. You can use this as a checklist of
+ * things to do to make sure your applications process file
+ * name encodings correctly.
+ * </para>
+ * <orderedlist>
+ * <listitem><para>
+ * If you get a file name from the file system from a function
+ * such as readdir(3) or gtk_file_chooser_get_filename(),
+ * you do not need to do any conversion to pass that
+ * file name to functions like open(2), rename(2), or
+ * fopen(3) — those are "raw" file names which the file
+ * system understands.
+ * </para></listitem>
+ * <listitem><para>
+ * If you need to display a file name, convert it to UTF-8 first by
+ * using g_filename_to_utf8(). If conversion fails, display a string like
+ * "<literal>Unknown file name</literal>". <emphasis>Do not</emphasis>
+ * convert this string back into the encoding used for file names if you
+ * wish to pass it to the file system; use the original file name instead.
+ * For example, the document window of a word processor could display
+ * "Unknown file name" in its title bar but still let the user save the
+ * file, as it would keep the raw file name internally. This can happen
+ * if the user has not set the <envar>G_FILENAME_ENCODING</envar>
+ * environment variable even though he has files whose names are not
+ * encoded in UTF-8.
+ * </para></listitem>
+ * <listitem><para>
+ * If your user interface lets the user type a file name for saving or
+ * renaming, convert it to the encoding used for file names in the file
+ * system by using g_filename_from_utf8(). Pass the converted file name
+ * to functions like fopen(3). If conversion fails, ask the user to enter
+ * a different file name. This can happen if the user types Japanese
+ * characters when <envar>G_FILENAME_ENCODING</envar> is set to
+ * <literal>ISO-8859-1</literal>, for example.
+ * </para></listitem>
+ * orderedlist>
+ * </refsect3>
+ * </refsect2>
+ */
+
/* We try to terminate strings in unknown charsets with this many zero bytes
* to ensure that multibyte strings really are nul-terminated when we return
* them from g_convert() and friends.
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