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

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<h3 class="section" id="Closure-Example-1"><span>2.6 Closure Example<a class="copiable-link" href="#Closure-Example-1"> &para;</a></span></h3>

<p>A trivial example that creates a new <code class="code">puts</code> by binding
<code class="code">fputs</code> with <code class="code">stdout</code>.
</p>
<div class="example">
<pre class="example-preformatted">#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;
}

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