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| 22 | <title>Calling Function Pointers (GNU C Language Manual)</title>
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| 30 | <link href="Symbol-Index.html" rel="index" title="Symbol Index">
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| 31 | <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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| 32 | <link href="Function-Pointers.html" rel="up" title="Function Pointers">
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| 33 | <link href="The-main-Function.html" rel="next" title="The main Function">
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| 57 | <body lang="en">
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| 58 | <span id="Calling-Function-Pointers"></span><div class="header">
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| 59 | <p>
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| 60 | Previous: <a href="Assigning-Function-Pointers.html" accesskey="p" rel="prev">Assigning Function Pointers</a>, Up: <a href="Function-Pointers.html" accesskey="u" rel="up">Function Pointers</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Symbol-Index.html" title="Index" rel="index">Index</a>]</p>
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| 61 | </div>
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| 62 | <hr>
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| 63 | <span id="Calling-Function-Pointers-1"></span><h4 class="subsection">22.5.3 Calling Function Pointers</h4>
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| 64 | <span id="index-calling-function-pointers"></span>
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| 65 | <span id="index-function-pointers_002c-calling"></span>
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| 66 |
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| 67 | <p>To call the function specified by a function pointer, just write the
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| 68 | function pointer value in a function call. For instance, here’s a
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| 69 | call to the function <code>binary_op</code> points to:
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| 70 | </p>
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| 71 | <div class="example">
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| 72 | <pre class="example">binary_op (x, 5)
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| 73 | </pre></div>
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| 74 |
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| 75 | <p>Since the data type of <code>binary_op</code> explicitly specifies type
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| 76 | <code>double</code> for the arguments, the call converts <code>x</code> and 5 to
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| 77 | <code>double</code>.
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| 78 | </p>
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| 79 | <p>The call conceptually dereferences the pointer <code>binary_op</code> to
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| 80 | “get” the function it points to, and calls that function. If you
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| 81 | wish, you can explicitly represent the derefence by writing the
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| 82 | <code>*</code> operator:
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| 83 | </p>
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| 84 | <div class="example">
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| 85 | <pre class="example">(*binary_op) (x, 5)
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| 86 | </pre></div>
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| 87 |
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| 88 | <p>The ‘<samp>*</samp>’ reminds people reading the code that <code>binary_op</code> is
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| 89 | a function pointer rather than the name of a specific function.
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| 90 | </p>
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| 91 |
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| 92 |
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| 93 |
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| 94 | </body>
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| 95 | </html>
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