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| 3 | <!-- Copyright (C) 2022 Richard Stallman and Free Software Foundation, Inc.
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| 5 | (The work of Trevis Rothwell and Nelson Beebe has been assigned or
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| 8 | Permission is granted to copy, distribute and/or modify this document
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| 20 | <head>
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| 21 | <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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| 22 | <title>Float Example (GNU C Language Manual)</title>
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| 23 |
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| 24 | <meta name="description" content="Float Example (GNU C Language Manual)">
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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="Beyond-Integers.html" rel="up" title="Beyond Integers">
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| 33 | <link href="Array-Example.html" rel="next" title="Array Example">
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| 55 | </head>
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| 56 |
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| 57 | <body lang="en">
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| 58 | <span id="Float-Example"></span><div class="header">
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| 59 | <p>
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| 60 | Next: <a href="Array-Example.html" accesskey="n" rel="next">Array Example</a>, Up: <a href="Beyond-Integers.html" accesskey="u" rel="up">Beyond Integers</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="An-Example-with-Non_002dInteger-Numbers"></span><h3 class="section">4.1 An Example with Non-Integer Numbers</h3>
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| 64 | <span id="index-floating-point-example"></span>
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| 65 |
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| 66 | <p>Here’s a function that operates on and returns <em>floating point</em>
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| 67 | numbers that don’t have to be integers. Floating point represents a
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| 68 | number as a fraction together with a power of 2. (For more detail,
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| 69 | see <a href="Floating_002dPoint-Data-Types.html">Floating-Point Data Types</a>.) This example calculates the
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| 70 | average of three floating point numbers that are passed to it as
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| 71 | arguments:
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| 72 | </p>
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| 73 | <div class="example">
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| 74 | <pre class="example">double
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| 75 | average_of_three (double a, double b, double c)
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| 76 | {
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| 77 | return (a + b + c) / 3;
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| 78 | }
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| 79 | </pre></div>
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| 80 |
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| 81 | <p>The values of the parameter <var>a</var>, <var>b</var> and <var>c</var> do not have to be
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| 82 | integers, and even when they happen to be integers, most likely their
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| 83 | average is not an integer.
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| 84 | </p>
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| 85 | <p><code>double</code> is the usual data type in C for calculations on
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| 86 | floating-point numbers.
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| 87 | </p>
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| 88 | <p>To print a <code>double</code> with <code>printf</code>, we must use ‘<samp>%f</samp>’
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| 89 | instead of ‘<samp>%d</samp>’:
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| 90 | </p>
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| 91 | <div class="example">
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| 92 | <pre class="example">printf ("Average is %f\n",
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| 93 | average_of_three (1.1, 9.8, 3.62));
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| 94 | </pre></div>
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| 95 |
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| 96 | <p>The code that calls <code>printf</code> must pass a <code>double</code> for
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| 97 | printing with ‘<samp>%f</samp>’ and an <code>int</code> for printing with ‘<samp>%d</samp>’.
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| 98 | If the argument has the wrong type, <code>printf</code> will produce garbage
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| 99 | output.
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| 100 | </p>
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| 101 | <p>Here’s a complete program that computes the average of three
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| 102 | specific numbers and prints the result:
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| 103 | </p>
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| 104 | <div class="example">
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| 105 | <pre class="example">double
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| 106 | average_of_three (double a, double b, double c)
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| 107 | {
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| 108 | return (a + b + c) / 3;
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| 109 | }
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| 110 |
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| 111 | int
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| 112 | main (void)
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| 113 | {
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| 114 | printf ("Average is %f\n",
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| 115 | average_of_three (1.1, 9.8, 3.62));
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| 116 | return 0;
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| 117 | }
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| 118 | </pre></div>
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| 119 |
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| 120 | <p>From now on we will not present examples of calls to <code>main</code>.
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| 121 | Instead we encourage you to write them for yourself when you want
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| 122 | to test executing some code.
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| 123 | </p>
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| 124 |
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| 125 |
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| 126 |
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| 127 | </body>
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| 128 | </html>
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