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| 22 | <title>Function Calls (GNU C Language Manual)</title>
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| 31 | <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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| 32 | <link href="Functions.html" rel="up" title="Functions">
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| 33 | <link href="Function-Call-Semantics.html" rel="next" title="Function Call Semantics">
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| 58 | <span id="Function-Calls"></span><div class="header">
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| 59 | <p>
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| 60 | Next: <a href="Function-Call-Semantics.html" accesskey="n" rel="next">Function Call Semantics</a>, Previous: <a href="Function-Declarations.html" accesskey="p" rel="prev">Function Declarations</a>, Up: <a href="Functions.html" accesskey="u" rel="up">Functions</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="Function-Calls-1"></span><h3 class="section">22.3 Function Calls</h3>
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| 64 | <span id="index-function-calls"></span>
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| 65 | <span id="index-calling-functions"></span>
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| 66 |
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| 67 | <p>Starting a program automatically calls the function named <code>main</code>
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| 68 | (see <a href="The-main-Function.html">The main Function</a>). Aside from that, a function does nothing
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| 69 | except when it is <em>called</em>. That occurs during the execution of a
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| 70 | function-call expression specifying that function.
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| 71 | </p>
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| 72 | <p>A function-call expression looks like this:
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| 73 | </p>
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| 74 | <div class="example">
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| 75 | <pre class="example"><var>function</var> (<var>arguments</var><span class="roman">…</span>)
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| 76 | </pre></div>
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| 77 |
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| 78 | <p>Most of the time, <var>function</var> is a function name. However, it can
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| 79 | also be an expression with a function pointer value; that way, the
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| 80 | program can determine at run time which function to call.
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| 81 | </p>
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| 82 | <p>The <var>arguments</var> are a series of expressions separated by commas.
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| 83 | Each expression specifies one argument to pass to the function.
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| 84 | </p>
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| 85 | <p>The list of arguments in a function call looks just like use of the
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| 86 | comma operator (see <a href="Comma-Operator.html">Comma Operator</a>), but the fact that it fills
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| 87 | the parentheses of a function call gives it a different meaning.
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| 88 | </p>
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| 89 | <p>Here’s an example of a function call, taken from an example near the
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| 90 | beginning (see <a href="Complete-Program.html">Complete Program</a>).
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| 91 | </p>
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| 92 | <div class="example">
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| 93 | <pre class="example">printf ("Fibonacci series item %d is %d\n",
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| 94 | 19, fib (19));
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| 95 | </pre></div>
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| 96 |
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| 97 | <p>The three arguments given to <code>printf</code> are a constant string, the
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| 98 | integer 19, and the integer returned by <code>fib (19)</code>.
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| 99 | </p>
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| 100 |
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| 101 |
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| 102 |
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| 104 | </html>
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