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<H1><A NAME="SECTION003900000000000000000"></A><A NAME="buildValue"></A>
<BR>
1.9 Building Arbitrary Values

</H1>

<P>
This function is the counterpart to <tt class="cfunction">PyArg_ParseTuple()</tt>.  It is
declared as follows:

<P>
<div class="verbatim"><pre>
PyObject *Py_BuildValue(char *format, ...);
</pre></div>

<P>
It recognizes a set of format units similar to the ones recognized by
<tt class="cfunction">PyArg_ParseTuple()</tt>, but the arguments (which are input to the
function, not output) must not be pointers, just values.  It returns a
new Python object, suitable for returning from a C function called
from Python.

<P>
One difference with <tt class="cfunction">PyArg_ParseTuple()</tt>: while the latter
requires its first argument to be a tuple (since Python argument lists
are always represented as tuples internally),
<tt class="cfunction">Py_BuildValue()</tt> does not always build a tuple.  It builds
a tuple only if its format string contains two or more format units.
If the format string is empty, it returns <code>None</code>; if it contains
exactly one format unit, it returns whatever object is described by
that format unit.  To force it to return a tuple of size 0 or one,
parenthesize the format string.

<P>
Examples (to the left the call, to the right the resulting Python value):

<P>
<div class="verbatim"><pre>
    Py_BuildValue("")                        None
    Py_BuildValue("i", 123)                  123
    Py_BuildValue("iii", 123, 456, 789)      (123, 456, 789)
    Py_BuildValue("s", "hello")              'hello'
    Py_BuildValue("ss", "hello", "world")    ('hello', 'world')
    Py_BuildValue("s#", "hello", 4)          'hell'
    Py_BuildValue("()")                      ()
    Py_BuildValue("(i)", 123)                (123,)
    Py_BuildValue("(ii)", 123, 456)          (123, 456)
    Py_BuildValue("(i,i)", 123, 456)         (123, 456)
    Py_BuildValue("[i,i]", 123, 456)         [123, 456]
    Py_BuildValue("{s:i,s:i}",
                  "abc", 123, "def", 456)    {'abc': 123, 'def': 456}
    Py_BuildValue("((ii)(ii)) (ii)",
                  1, 2, 3, 4, 5, 6)          (((1, 2), (3, 4)), (5, 6))
</pre></div>

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<span class="release-info">Release 2.4.2, documentation updated on 28 September 2005.</span>
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