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<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision: 297078 $ -->
<sect2 xml:id="internals2.ze1.zendapi.returning" xmlns="http://docbook.org/ns/docbook">
<title>Returning Values</title>
<para>
Returning values from your functions to PHP was described briefly
in an earlier section; this section gives the details. Return
values are passed via the <envar>return_value</envar> variable,
which is passed to your functions as argument. The
<envar>return_value</envar> argument consists of a
<envar>zval</envar> container (see the earlier discussion of the
call interface) that you can freely modify. The container itself is
already allocated, so you don't have to run
<literal>MAKE_STD_ZVAL</literal> on it. Instead, you can access its
members directly.
</para>
<para>
To make returning values from functions easier and to prevent
hassles with accessing the internal structures of the
<envar>zval</envar> container, a set of predefined macros is
available (as usual). These macros automatically set the
correspondent type and value, as described in
<xref linkend="internals2.ze1.zendapi.tab.return"/> and <xref linkend="internals2.ze1.zendapi.tab.retval"/>.
</para>
<note>
<para>
The macros in <xref linkend="internals2.ze1.zendapi.tab.return"/> automatically
<emphasis>return</emphasis> from your function, those in
<xref linkend="internals2.ze1.zendapi.tab.retval"/> only <emphasis>set</emphasis>
the return value; they don't return from your function.
</para>
</note>
<table xml:id="internals2.ze1.zendapi.tab.return">
<title>Predefined Macros for Returning Values from a
Function</title>
<tgroup cols="2">
<colspec colnum="1" colname="col1" colwidth="*"/>
<colspec colnum="2" colname="col2" colwidth="*"/>
<tbody>
<row>
<entry colname="col1">Macro</entry>
<entry colname="col2">Description</entry>
</row>
<row>
<entry colname="col1"><literal>RETURN_RESOURCE(resource)</literal></entry>
<entry colname="col2">Returns a resource.</entry>
</row>
<row>
<entry colname="col1"><literal>RETURN_BOOL(bool)</literal></entry>
<entry colname="col2">Returns a Boolean.</entry>
</row>
<row>
<entry colname="col1"><literal>RETURN_NULL()</literal></entry>
<entry colname="col2">Returns nothing (a NULL value).</entry>
</row>
<row>
<entry colname="col1"><literal>RETURN_LONG(long)</literal></entry>
<entry colname="col2">Returns a long.</entry>
</row>
<row>
<entry colname="col1"><literal>RETURN_DOUBLE(double)</literal></entry>
<entry colname="col2">Returns a double.</entry>
</row>
<row>
<entry colname="col1">
<literal>RETURN_STRING(string, duplicate)</literal>
</entry>
<entry colname="col2">
Returns a string. The <envar>duplicate</envar> flag indicates
whether the string should be duplicated using
<function>estrdup</function>.
</entry>
</row>
<row>
<entry colname="col1">
<literal>RETURN_STRINGL(string, length, duplicate)</literal>
</entry>
<entry colname="col2">
Returns a string of the specified length; otherwise, behaves
like <literal>RETURN_STRING</literal>. This macro is faster
and binary-safe, however.
</entry>
</row>
<row>
<entry colname="col1"><literal>RETURN_EMPTY_STRING()</literal></entry>
<entry colname="col2">Returns an empty string.</entry>
</row>
<row>
<entry colname="col1"><literal>RETURN_FALSE</literal></entry>
<entry colname="col2">Returns Boolean false.</entry>
</row>
<row>
<entry colname="col1"><literal>RETURN_TRUE</literal></entry>
<entry colname="col2">Returns Boolean true.</entry>
</row>
</tbody>
</tgroup>
</table>
<table xml:id="internals2.ze1.zendapi.tab.retval">
<title>Predefined Macros for Setting the Return Value
of a Function</title>
<tgroup cols="2">
<colspec colnum="1" colname="col1" colwidth="*"/>
<colspec colnum="2" colname="col2" colwidth="*"/>
<tbody>
<row>
<entry colname="col1">Macro</entry>
<entry colname="col2">Description</entry>
</row>
<row>
<entry colname="col1"><literal>RETVAL_RESOURCE(resource)</literal></entry>
<entry colname="col2">Sets the return value to the specified
resource.</entry>
</row>
<row>
<entry colname="col1"><literal>RETVAL_BOOL(bool)</literal></entry>
<entry colname="col2">Sets the return value to the specified
Boolean value.</entry>
</row>
<row>
<entry colname="col1"><literal>RETVAL_NULL</literal></entry>
<entry colname="col2">Sets the return value to NULL.</entry>
</row>
<row>
<entry colname="col1"><literal>RETVAL_LONG(long)</literal></entry>
<entry colname="col2">
Sets the return value to the specified long.
</entry>
</row>
<row>
<entry colname="col1"><literal>RETVAL_DOUBLE(double)</literal></entry>
<entry colname="col2">
Sets the return value to the specified double.
</entry>
</row>
<row>
<entry colname="col1">
<literal>RETVAL_STRING(string, duplicate)</literal>
</entry>
<entry colname="col2">
Sets the return value to the specified string and duplicates
it to Zend internal memory if desired (see also
<literal>RETURN_STRING</literal>).
</entry>
</row>
<row>
<entry colname="col1">
<literal>RETVAL_STRINGL(string, length, duplicate)</literal>
</entry>
<entry colname="col2">
Sets the return value to the specified string and forces the
length to become <envar>length</envar> (see also
<literal>RETVAL_STRING</literal>). This macro is faster and
binary-safe, and should be used whenever the string length is
known.
</entry>
</row>
<row>
<entry colname="col1">
<literal>RETVAL_EMPTY_STRING</literal>
</entry>
<entry colname="col2">
Sets the return value to an empty string.
</entry>
</row>
<row>
<entry colname="col1"><literal>RETVAL_FALSE</literal></entry>
<entry colname="col2">
Sets the return value to Boolean false.
</entry>
</row>
<row>
<entry colname="col1"><literal>RETVAL_TRUE</literal></entry>
<entry colname="col2">
Sets the return value to Boolean true.
</entry>
</row>
</tbody>
</tgroup>
</table>
<para>
Complex types such as arrays and objects can be returned by using
<function>array_init</function> and
<function>object_init</function>, as well as the corresponding hash
functions on <envar>return_value</envar>. Since these types cannot
be constructed of trivial information, there are no predefined
macros for them.
</para>
</sect2>
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