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<a name="Complex-Type-Example"></a>
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<p>
Previous: <a href="Complex.html#Complex" accesskey="p" rel="prev">Complex</a>, Up: <a href="Types.html#Types" accesskey="u" rel="up">Types</a> &nbsp; [<a href="Index.html#Index" title="Index" rel="index">Index</a>]</p>
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<a name="Complex-Type-Example-1"></a>
<h4 class="subsection">2.3.5 Complex Type Example</h4>

<p>This example demonstrates how to use complex types:
</p>
<div class="example">
<pre class="example">#include &lt;stdio.h&gt;
#include &lt;ffi.h&gt;
#include &lt;complex.h&gt;

void complex_fn(_Complex float cf,
                _Complex double cd,
                _Complex long double cld)
{
  printf(&quot;cf=%f+%fi\ncd=%f+%fi\ncld=%f+%fi\n&quot;,
         (float)creal (cf), (float)cimag (cf),
         (float)creal (cd), (float)cimag (cd),
         (float)creal (cld), (float)cimag (cld));
}

int main()
{
  ffi_cif cif;
  ffi_type *args[3];
  void *values[3];
  _Complex float cf;
  _Complex double cd;
  _Complex long double cld;

  /* Initialize the argument info vectors */
  args[0] = &amp;ffi_type_complex_float;
  args[1] = &amp;ffi_type_complex_double;
  args[2] = &amp;ffi_type_complex_longdouble;
  values[0] = &amp;cf;
  values[1] = &amp;cd;
  values[2] = &amp;cld;

  /* Initialize the cif */
  if (ffi_prep_cif(&amp;cif, FFI_DEFAULT_ABI, 3,
                   &amp;ffi_type_void, args) == FFI_OK)
    {
      cf = 1.0 + 20.0 * I;
      cd = 300.0 + 4000.0 * I;
      cld = 50000.0 + 600000.0 * I;
      /* Call the function */
      ffi_call(&amp;cif, (void (*)(void))complex_fn, 0, values);
    }

  return 0;
}
</pre></div>

<p>This is an example for defining a custom complex type descriptor
for compilers that support them:
</p>
<div class="example">
<pre class="example">/*
 * This macro can be used to define new complex type descriptors
 * in a platform independent way.
 *
 * name: Name of the new descriptor is ffi_type_complex_&lt;name&gt;.
 * type: The C base type of the complex type.
 */
#define FFI_COMPLEX_TYPEDEF(name, type, ffitype)             \
  static ffi_type *ffi_elements_complex_##name [2] = {      \
    (ffi_type *)(&amp;ffitype), NULL                             \
  };                                                        \
  struct struct_align_complex_##name {                      \
    char c;                                                  \
    _Complex type x;                                         \
  };                                                        \
  ffi_type ffi_type_complex_##name = {                      \
    sizeof(_Complex type),                                   \
    offsetof(struct struct_align_complex_##name, x),         \
    FFI_TYPE_COMPLEX,                                        \
    (ffi_type **)ffi_elements_complex_##name                 \
  }

/* Define new complex type descriptors using the macro: */
/* ffi_type_complex_sint */
FFI_COMPLEX_TYPEDEF(sint, int, ffi_type_sint);
/* ffi_type_complex_uchar */
FFI_COMPLEX_TYPEDEF(uchar, unsigned char, ffi_type_uint8);
</pre></div>

<p>The new type descriptors can then be used like one of the built-in
type descriptors in the previous example.
</p>



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libffi-dev 3.2.1-6 / usr / share / doc / libffi6 / html / Complex-Type-Example.html
