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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">	<html>		<head>			<title>page_412</title>			<link rel="stylesheet" href="reset.css" type="text/css" media="all">			<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />		</head>		<body>		<table summary="top nav" border="0" width="100%">			<tr>				<td align="left" width="30%" style="background: #EEF3E2"><a style="color: blue; font-size: 120%; font-weight: bold; text-decoration: none; font-family: verdana;" href="page_411.html">&lt;&nbsp;previous page</a></td>				<td align="center" width="40%" style="background: #EEF3E2"><strong style="color: #2F4F4F; font-size: 120%;">page_412</strong></td>				<td align="right" width="30%" style="background: #EEF3E2"><a style="color: blue; font-size: 120%; font-weight: bold; text-decoration: none; font-family: verdana;" href="page_413.html">next page&nbsp;&gt;</a></td>			</tr>					<tr>				<td align="left" colspan="3" style="background: #ffffff; padding: 20px;">    <table border="0" width="100%" cellpadding="0"><tr><td align="center">  <table border="0" cellpadding="2" cellspacing="0" width="100%"><tr><td align="left"></td>  <td align="right"></td>  </tr></table></td></tr><tr><td align="left"><p></p><table border="0" cellspacing="0" cellpadding="0" width="100%"><tr><td align="right"><font face="Times New Roman, Times, Serif" size="2" color="#FF0000">Page 412</font></td></tr></table><table border="0" cellspacing="0" cellpadding="0"><tr><td rowspan="5"></td>  <td colspan="3" height="12"></td>  <td rowspan="5"></td></tr><tr><td colspan="3"></td></tr><tr><td></td>  <td><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">聽聽聽聽return聽result;<br />}</font></td><td></td></tr><tr><td colspan="3"></td></tr><tr><td colspan="3" height="1"></td></tr></table><table border="0" cellspacing="0" cellpadding="0"><tr><td rowspan="5"></td>  <td colspan="3" height="12"></td>  <td rowspan="5"></td></tr><tr><td colspan="3"></td></tr><tr><td></td>  <td><font face="Times New Roman, Times, Serif" size="3">A call to the </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">Factorial</font><font face="Times New Roman, Times, Serif" size="3"> function might look like this:</font></td><td></td></tr><tr><td colspan="3"></td></tr><tr><td colspan="3" height="1"></td></tr></table><table border="0" cellspacing="0" cellpadding="0"><tr><td rowspan="5"></td>  <td colspan="3" height="12"></td>  <td rowspan="5"></td></tr><tr><td colspan="3"></td></tr><tr><td></td>  <td><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">combinations聽=聽Factorial(n)聽/聽(Factorial(m)聽*聽Factorial(n聽-聽m));</font></td><td></td></tr><tr><td colspan="3"></td></tr><tr><td colspan="3" height="1"></td></tr></table><table border="0" cellspacing="0" cellpadding="0"><tr><td rowspan="5"></td>  <td colspan="3" height="12"></td>  <td rowspan="5"></td></tr><tr><td colspan="3"></td></tr><tr><td></td>  <td><font face="Times New Roman, Times, Serif" size="3"><i>Boolean Functions</i></font></td><td></td></tr><tr><td colspan="3"></td></tr><tr><td colspan="3" height="1"></td></tr></table><table border="0" cellspacing="0" cellpadding="0"><tr><td rowspan="5"></td>  <td colspan="3" height="12"></td>  <td rowspan="5"></td></tr><tr><td colspan="3"></td></tr><tr><td></td>  <td><font face="Times New Roman, Times, Serif" size="3">Value-returning functions are not restricted to returning numerical results. We can also use them to evaluate a condition and return a Boolean result. Boolean functions can be useful when a branch or loop depends on some complex condition. Rather than code the condition directly into the If or While statement, we can call a Boolean function to form the controlling expression.</font></td><td></td></tr><tr><td colspan="3"></td></tr><tr><td colspan="3" height="1"></td></tr></table><table border="0" cellspacing="0" cellpadding="0"><tr><td rowspan="5"></td>  <td colspan="3" height="12"></td>  <td rowspan="5"></td></tr><tr><td colspan="3"></td></tr><tr><td></td>  <td><font face="Times New Roman, Times, Serif" size="3">Suppose we are writing a program that works with triangles. The program reads three angles as floating point numbers. Before performing any calculations on those angles, however, we want to check that they really form a triangle by adding the angles to confirm that their sum equals 180 degrees. We can write a value-returning function that takes the three angles as parameters and returns a Boolean result. Such a function would look like this (recall from Chapter 5 that you should test floating point numbers only for near equality):</font></td><td></td></tr><tr><td colspan="3"></td></tr><tr><td colspan="3" height="1"></td></tr></table><table border="0" cellspacing="0" cellpadding="0"><tr><td rowspan="5"></td>  <td colspan="3" height="12"></td>  <td rowspan="5"></td></tr><tr><td colspan="3"></td></tr><tr><td></td>  <td><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">#include聽&lt;math.h&gt;聽聽聽//聽For聽fabs()<br />.<br />.<br />.<br />typedef聽int聽Boolean;<br />const聽Boolean聽TRUE聽=聽1;<br />const聽Boolean聽FALSE聽=聽0;<br />.<br />.<br />.<br />Boolean聽IsTriangle(聽/*聽in聽*/聽float聽angle1,聽聽聽聽//聽First聽angle<br />聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽/*聽in聽*/聽float聽angle2,聽聽聽聽//聽Second聽angle<br />聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽/*聽in聽*/聽float聽angle3聽)聽聽聽//聽Third聽angle<br /><br />//聽This聽function聽checks聽to聽see聽if聽its聽three聽incoming聽values<br />//聽add聽up聽to聽180聽degrees,聽forming聽a聽valid聽triangle<br /><br />//聽Precondition:<br />//聽聽聽聽聽angle1,聽angle2,聽and聽angle3聽are聽assigned<br />//聽Postcondition:<br />//聽聽聽聽聽Function聽value聽==聽TRUE,聽if聽(angle1聽+聽angle2聽+聽angle3)聽is<br />//聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽within聽0.00000001聽of聽180.0聽degrees<br />//聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽==聽FALSE,聽otherwise<br /><br />{<br /></font></td><td></td></tr><tr><td colspan="3"></td></tr><tr><td colspan="3" height="1"></td></tr></table></td></tr></table><p><font size="0"></font></p>聽  </td>			</tr>				<tr>				<td align="left" width="30%" style="background: #EEF3E2"><a style="color: blue; font-size: 120%; font-weight: bold; text-decoration: none; font-family: verdana;" href="page_411.html">&lt;&nbsp;previous page</a></td>				<td align="center" width="40%" style="background: #EEF3E2"><strong style="color: #2F4F4F; font-size: 120%;">page_412</strong></td>				<td align="right" width="30%" style="background: #EEF3E2"><a style="color: blue; font-size: 120%; font-weight: bold; text-decoration: none; font-family: verdana;" href="page_413.html">next page&nbsp;&gt;</a></td>			</tr>		</table>		</body>	</html>
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