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<title>Closure Example (libffi: the portable foreign function interface library)</title>

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<p>
Next: <a href="Thread-Safety.html" accesskey="n" rel="next">Thread Safety</a>, Previous: <a href="The-Closure-API.html" accesskey="p" rel="prev">The Closure API</a>, Up: <a href="Using-libffi.html" accesskey="u" rel="up">Using libffi</a> &nbsp; [<a href="Index.html" title="Index" rel="index">Index</a>]</p>
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<hr>
<span id="Closure-Example-1"></span><h3 class="section">2.6 Closure Example</h3>

<p>A trivial example that creates a new <code>puts</code> by binding
<code>fputs</code> with <code>stdout</code>.
</p>
<div class="example">
<pre class="example">#include &lt;stdio.h&gt;
#include &lt;ffi.h&gt;

/* Acts like puts with the file given at time of enclosure. */
void puts_binding(ffi_cif *cif, void *ret, void* args[],
                  void *stream)
{
  *(ffi_arg *)ret = fputs(*(char **)args[0], (FILE *)stream);
}

typedef int (*puts_t)(char *);

int main()
{
  ffi_cif cif;
  ffi_type *args[1];
  ffi_closure *closure;

  void *bound_puts;
  int rc;

  /* Allocate closure and bound_puts */
  closure = ffi_closure_alloc(sizeof(ffi_closure), &amp;bound_puts);

  if (closure)
    {
      /* Initialize the argument info vectors */
      args[0] = &amp;ffi_type_pointer;

      /* Initialize the cif */
      if (ffi_prep_cif(&amp;cif, FFI_DEFAULT_ABI, 1,
                       &amp;ffi_type_sint, args) == FFI_OK)
        {
          /* Initialize the closure, setting stream to stdout */
          if (ffi_prep_closure_loc(closure, &amp;cif, puts_binding,
                                   stdout, bound_puts) == FFI_OK)
            {
              rc = ((puts_t)bound_puts)(&quot;Hello World!&quot;);
              /* rc now holds the result of the call to fputs */
            }
        }
    }

  /* Deallocate both closure, and bound_puts */
  ffi_closure_free(closure);

  return 0;
}

</pre></div>

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Name	Size	Permission
Arrays-Unions-Enums.html	7268 bytes	0644
Closure-Example.html	4877 bytes	0644
Complex-Type-Example.html	6087 bytes	0644
Complex.html	5366 bytes	0644
Index.html	15485 bytes	0644
Introduction.html	5245 bytes	0644
Memory-Usage.html	4722 bytes	0644
Missing-Features.html	3680 bytes	0644
Multiple-ABIs.html	3716 bytes	0644
Primitive-Types.html	9533 bytes	0644
Simple-Example.html	4295 bytes	0644
Size-and-Alignment.html	6311 bytes	0644
Structures.html	4920 bytes	0644
The-Basics.html	10143 bytes	0644
The-Closure-API.html	8811 bytes	0644
Thread-Safety.html	4052 bytes	0644
Type-Example.html	4631 bytes	0644
Types.html	3950 bytes	0644
Using-libffi.html	3902 bytes	0644
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File Content: Closure-Example.html

File Content: `Closure-Example.html`