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<h1 class="chapter"> <a href="libunistring_toc.html#TOC30">5. Conversions between Unicode and encodings <code><uniconv.h></code></a> </h1>
<p>This include file declares functions for converting between Unicode strings
and <code>char *</code> strings in locale encoding or in other specified encodings.
</p>
<a name="IDX148"></a>
<p>The following function returns the locale encoding.
</p>
<dl>
<dt><u>Function:</u> const char * <b>locale_charset</b><i> ()</i>
<a name="IDX149"></a>
</dt>
<dd><p>Determines the current locale's character encoding, and canonicalizes it
into one of the canonical names listed in ‘<tt>localcharset.h</tt>’.
If the canonical name cannot be determined, the result is a non-canonical
name.
</p>
<p>The result must not be freed; it is statically allocated.
</p>
<p>The result of this function can be used as an argument to the <code>iconv_open</code>
function in GNU libc, in GNU libiconv, or in the gnulib provided wrapper
around the native <code>iconv_open</code> function. It may not work as an argument
to the native <code>iconv_open</code> function directly.
</p></dd></dl>
<p>The handling of unconvertible characters during the conversions can be
parametrized through the following enumeration type:
</p>
<dl>
<dt><u>Type:</u> <b>enum iconv_ilseq_handler</b>
<a name="IDX150"></a>
</dt>
<dd><p>This type specifies how unconvertible characters in the input are handled.
</p></dd></dl>
<dl>
<dt><u>Constant:</u> enum iconv_ilseq_handler <b>iconveh_error</b>
<a name="IDX151"></a>
</dt>
<dd><p>This handler causes the function to return with <code>errno</code> set to
<code>EILSEQ</code>.
</p></dd></dl>
<dl>
<dt><u>Constant:</u> enum iconv_ilseq_handler <b>iconveh_question_mark</b>
<a name="IDX152"></a>
</dt>
<dd><p>This handler produces one question mark ‘<samp>?</samp>’ per unconvertible character.
</p></dd></dl>
<dl>
<dt><u>Constant:</u> enum iconv_ilseq_handler <b>iconveh_question_replacement_character</b>
<a name="IDX153"></a>
</dt>
<dd><p>This handler produces one U+FFFD per unconvertible character if that
fits in the target encoding, otherwise one question mark ‘<samp>?</samp>’ per
unconvertible character.
</p></dd></dl>
<dl>
<dt><u>Constant:</u> enum iconv_ilseq_handler <b>iconveh_escape_sequence</b>
<a name="IDX154"></a>
</dt>
<dd><p>This handler produces an escape sequence <code>\u<var>xxxx</var></code> or
<code>\U<var>xxxxxxxx</var></code> for each unconvertible character.
</p></dd></dl>
<a name="IDX155"></a>
<p>The following functions convert between strings in a specified encoding and
Unicode strings.
</p>
<dl>
<dt><u>Function:</u> uint8_t * <b>u8_conv_from_encoding</b><i> (const char *<var>fromcode</var>, enum iconv_ilseq_handler <var>handler</var>, const char *<var>src</var>, size_t <var>srclen</var>, size_t *<var>offsets</var>, uint8_t *<var>resultbuf</var>, size_t *<var>lengthp</var>)</i>
<a name="IDX156"></a>
</dt>
<dt><u>Function:</u> uint16_t * <b>u16_conv_from_encoding</b><i> (const char *<var>fromcode</var>, enum iconv_ilseq_handler <var>handler</var>, const char *<var>src</var>, size_t <var>srclen</var>, size_t *<var>offsets</var>, uint16_t *<var>resultbuf</var>, size_t *<var>lengthp</var>)</i>
<a name="IDX157"></a>
</dt>
<dt><u>Function:</u> uint32_t * <b>u32_conv_from_encoding</b><i> (const char *<var>fromcode</var>, enum iconv_ilseq_handler <var>handler</var>, const char *<var>src</var>, size_t <var>srclen</var>, size_t *<var>offsets</var>, uint32_t *<var>resultbuf</var>, size_t *<var>lengthp</var>)</i>
<a name="IDX158"></a>
</dt>
<dd><p>Converts an entire string, possibly including NUL bytes, from one encoding
to UTF-8 encoding.
</p>
<p>Converts a memory region given in encoding <var>fromcode</var>. <var>fromcode</var> is
as for the <code>iconv_open</code> function.
</p>
<p>The input is in the memory region between <var>src</var> (inclusive) and
<code><var>src</var> + <var>srclen</var></code> (exclusive).
</p>
<p>If <var>offsets</var> is not NULL, it should point to an array of <var>srclen</var>
integers; this array is filled with offsets into the result, i.e. the
character starting at <code><var>src</var>[i]</code> corresponds to the character starting
at <code><var>result</var>[<var>offsets</var>[i]]</code>, and other offsets are set to
<code>(size_t)(-1)</code>.
</p>
<p><code><var>resultbuf</var></code> and <code>*<var>lengthp</var></code> should be a scratch
buffer and its size, or <code><var>resultbuf</var></code> can be NULL.
</p>
<p>May erase the contents of the memory at <code><var>resultbuf</var></code>.
</p>
<p>If successful: The resulting Unicode string (non-NULL) is returned and
its length stored in <code>*<var>lengthp</var></code>. The resulting string is
<code><var>resultbuf</var></code> if no dynamic memory allocation was necessary,
or a freshly allocated memory block otherwise.
</p>
<p>In case of error: NULL is returned and <code>errno</code> is set.
Particular <code>errno</code> values: <code>EINVAL</code>, <code>EILSEQ</code>, <code>ENOMEM</code>.
</p></dd></dl>
<dl>
<dt><u>Function:</u> char * <b>u8_conv_to_encoding</b><i> (const char *<var>tocode</var>, enum iconv_ilseq_handler <var>handler</var>, const uint8_t *<var>src</var>, size_t <var>srclen</var>, size_t *<var>offsets</var>, char *<var>resultbuf</var>, size_t *<var>lengthp</var>)</i>
<a name="IDX159"></a>
</dt>
<dt><u>Function:</u> char * <b>u16_conv_to_encoding</b><i> (const char *<var>tocode</var>, enum iconv_ilseq_handler <var>handler</var>, const uint16_t *<var>src</var>, size_t <var>srclen</var>, size_t *<var>offsets</var>, char *<var>resultbuf</var>, size_t *<var>lengthp</var>)</i>
<a name="IDX160"></a>
</dt>
<dt><u>Function:</u> char * <b>u32_conv_to_encoding</b><i> (const char *<var>tocode</var>, enum iconv_ilseq_handler <var>handler</var>, const uint32_t *<var>src</var>, size_t <var>srclen</var>, size_t *<var>offsets</var>, char *<var>resultbuf</var>, size_t *<var>lengthp</var>)</i>
<a name="IDX161"></a>
</dt>
<dd><p>Converts an entire Unicode string, possibly including NUL units, from UTF-8
encoding to a given encoding.
</p>
<p>Converts a memory region to encoding <var>tocode</var>. <var>tocode</var> is as for
the <code>iconv_open</code> function.
</p>
<p>The input is in the memory region between <var>src</var> (inclusive) and
<code><var>src</var> + <var>srclen</var></code> (exclusive).
</p>
<p>If <var>offsets</var> is not NULL, it should point to an array of <var>srclen</var>
integers; this array is filled with offsets into the result, i.e. the
character starting at <code><var>src</var>[i]</code> corresponds to the character starting
at <code><var>result</var>[<var>offsets</var>[i]]</code>, and other offsets are set to
<code>(size_t)(-1)</code>.
</p>
<p><code><var>resultbuf</var></code> and <code>*<var>lengthp</var></code> should be a scratch
buffer and its size, or <code><var>resultbuf</var></code> can be NULL.
</p>
<p>May erase the contents of the memory at <code><var>resultbuf</var></code>.
</p>
<p>If successful: The resulting Unicode string (non-NULL) is returned and
its length stored in <code>*<var>lengthp</var></code>. The resulting string is
<code><var>resultbuf</var></code> if no dynamic memory allocation was necessary,
or a freshly allocated memory block otherwise.
</p>
<p>In case of error: NULL is returned and <code>errno</code> is set.
Particular <code>errno</code> values: <code>EINVAL</code>, <code>EILSEQ</code>, <code>ENOMEM</code>.
</p></dd></dl>
<p>The following functions convert between NUL terminated strings in a specified
encoding and NUL terminated Unicode strings.
</p>
<dl>
<dt><u>Function:</u> uint8_t * <b>u8_strconv_from_encoding</b><i> (const char *<var>string</var>, const char *<var>fromcode</var>, enum iconv_ilseq_handler <var>handler</var>)</i>
<a name="IDX162"></a>
</dt>
<dt><u>Function:</u> uint16_t * <b>u16_strconv_from_encoding</b><i> (const char *<var>string</var>, const char *<var>fromcode</var>, enum iconv_ilseq_handler <var>handler</var>)</i>
<a name="IDX163"></a>
</dt>
<dt><u>Function:</u> uint32_t * <b>u32_strconv_from_encoding</b><i> (const char *<var>string</var>, const char *<var>fromcode</var>, enum iconv_ilseq_handler <var>handler</var>)</i>
<a name="IDX164"></a>
</dt>
<dd><p>Converts a NUL terminated string from a given encoding.
</p>
<p>The result is <code>malloc</code> allocated, or NULL (with <var>errno</var> set) in case of error.
</p>
<p>Particular <code>errno</code> values: <code>EILSEQ</code>, <code>ENOMEM</code>.
</p></dd></dl>
<dl>
<dt><u>Function:</u> char * <b>u8_strconv_to_encoding</b><i> (const uint8_t *<var>string</var>, const char *<var>tocode</var>, enum iconv_ilseq_handler <var>handler</var>)</i>
<a name="IDX165"></a>
</dt>
<dt><u>Function:</u> char * <b>u16_strconv_to_encoding</b><i> (const uint16_t *<var>string</var>, const char *<var>tocode</var>, enum iconv_ilseq_handler <var>handler</var>)</i>
<a name="IDX166"></a>
</dt>
<dt><u>Function:</u> char * <b>u32_strconv_to_encoding</b><i> (const uint32_t *<var>string</var>, const char *<var>tocode</var>, enum iconv_ilseq_handler <var>handler</var>)</i>
<a name="IDX167"></a>
</dt>
<dd><p>Converts a NUL terminated string to a given encoding.
</p>
<p>The result is <code>malloc</code> allocated, or NULL (with <code>errno</code> set) in case of error.
</p>
<p>Particular <code>errno</code> values: <code>EILSEQ</code>, <code>ENOMEM</code>.
</p></dd></dl>
<p>The following functions are shorthands that convert between NUL terminated
strings in locale encoding and NUL terminated Unicode strings.
</p>
<dl>
<dt><u>Function:</u> uint8_t * <b>u8_strconv_from_locale</b><i> (const char *<var>string</var>)</i>
<a name="IDX168"></a>
</dt>
<dt><u>Function:</u> uint16_t * <b>u16_strconv_from_locale</b><i> (const char *<var>string</var>)</i>
<a name="IDX169"></a>
</dt>
<dt><u>Function:</u> uint32_t * <b>u32_strconv_from_locale</b><i> (const char *<var>string</var>)</i>
<a name="IDX170"></a>
</dt>
<dd><p>Converts a NUL terminated string from the locale encoding.
</p>
<p>The result is <code>malloc</code> allocated, or NULL (with <code>errno</code> set) in case of error.
</p>
<p>Particular <code>errno</code> values: <code>ENOMEM</code>.
</p></dd></dl>
<dl>
<dt><u>Function:</u> char * <b>u8_strconv_to_locale</b><i> (const uint8_t *<var>string</var>)</i>
<a name="IDX171"></a>
</dt>
<dt><u>Function:</u> char * <b>u16_strconv_to_locale</b><i> (const uint16_t *<var>string</var>)</i>
<a name="IDX172"></a>
</dt>
<dt><u>Function:</u> char * <b>u32_strconv_to_locale</b><i> (const uint32_t *<var>string</var>)</i>
<a name="IDX173"></a>
</dt>
<dd><p>Converts a NUL terminated string to the locale encoding.
</p>
<p>The result is <code>malloc</code> allocated, or NULL (with <code>errno</code> set) in case of error.
</p>
<p>Particular <code>errno</code> values: <code>ENOMEM</code>.
</p></dd></dl>
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