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📁 Programming and Problem Solving with C++
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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_278</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_277.html">&lt;&nbsp;previous page</a></td>				<td align="center" width="40%" style="background: #EEF3E2"><strong style="color: #2F4F4F; font-size: 120%;">page_278</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_279.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 278</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="Times New Roman, Times, Serif" size="3">If statement can contain other While and If statements. By nesting, we can create complex control structures.</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 want to extend our code for counting commas on one line, repeating it for all the lines in a file. We put an EOF-controlled loop around it:</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">cin.get(inChar);聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽//聽Initialize聽outer聽loop<br />while聽(cin)聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽//聽Outer聽loop聽test<br />{<br />聽聽聽聽commaCount聽=聽0;聽聽聽聽聽聽聽聽聽聽聽聽//聽Initialize聽inner聽loop<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聽聽//聽聽聽(Priming聽read聽is聽taken聽care聽of<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聽聽//聽聽聽聽by聽outer聽loop's聽priming聽read)<br />聽聽聽聽while聽(inChar聽!=聽\n)聽聽聽聽聽//聽Inner聽loop聽test<br />聽聽聽聽{<br />聽聽聽聽聽聽聽聽if聽(inChar聽==聽,)<br />聽聽聽聽聽聽聽聽聽聽聽聽commaCount++;<br />聽聽聽聽聽聽聽聽cin.get(inChar);聽聽聽聽聽聽聽//聽Update聽inner聽termination聽condition<br />聽聽聽聽}<br />聽聽聽聽cout聽&lt;&lt;聽commaCount聽&lt;&lt;聽endl;<br />聽聽聽聽cin.get(inChar);聽聽聽聽聽聽聽聽聽聽聽//聽Update聽outer聽termination聽condition<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">In this code, notice that we have omitted the priming read for the inner loop. The priming read for the outer loop has already primed the pump. It would be a mistake to include another priming read just before the inner loop; the character read by the outer priming read would be destroyed before we could test it.</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">Let's examine the general pattern of a simple nested loop:</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">Initialize聽outer聽loop<br />while聽(Outer聽loop聽condition)<br />{<br />聽聽.<br />聽聽.<br />聽聽.<br />聽Initialize聽inner聽loop<br />聽while聽(Inner聽loop聽condition)<br />聽{<br />聽聽Inner聽loop聽processing聽and聽update<br />聽}<br />聽聽.<br />聽聽.<br />聽聽.<br />聽Outer聽loop聽update<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">Notice that each loop has its own initialization, test, and update. The dots represent places where processing may take place in the outer loop. It's pos-</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_277.html">&lt;&nbsp;previous page</a></td>				<td align="center" width="40%" style="background: #EEF3E2"><strong style="color: #2F4F4F; font-size: 120%;">page_278</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_279.html">next page&nbsp;&gt;</a></td>			</tr>		</table>		</body>	</html>
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