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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_922</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_921.html">< previous page</a></td> <td align="center" width="40%" style="background: #EEF3E2"><strong style="color: #2F4F4F; font-size: 120%;">page_922</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_923.html">next page ></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 922</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">public:<br />聽聽聽聽void聽Punch(聽/*聽in聽*/聽int聽hours,<br />聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽/*聽in聽*/聽int聽minutes,<br />聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽/*聽in聽*/聽int聽seconds聽);<br />聽聽聽聽void聽Print()聽const;<br />聽聽聽聽聽.<br />聽聽聽聽聽.<br />聽聽聽聽聽.<br />聽聽聽聽TimeCard(聽/*聽in聽*/聽long聽idNum,<br />聽聽聽聽聽聽聽聽聽聽聽聽聽聽/*聽in聽*/聽int聽聽initHrs,<br />聽聽聽聽聽聽聽聽聽聽聽聽聽聽/*聽in聽*/聽int聽聽initMins,<br />聽聽聽聽聽聽聽聽聽聽聽聽聽聽/*聽in聽*/聽int聽聽initSecs聽);<br />聽聽聽聽TimeCard()聽;<br />private:<br />聽聽聽聽long聽id;<br />聽聽聽聽Time聽timeStamp;<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 designing the </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">TimeCard</font><font face="Times New Roman, Times, Serif" size="3"> class, you have used composition; a </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">TimeCard</font><font face="Times New Roman, Times, Serif" size="3"> object is composed of a </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">Time</font><font face="Times New Roman, Times, Serif" size="3"> object (and a </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">long</font><font face="Times New Roman, Times, Serif" size="3"> variable). Composition creates a <i>has-a relationship</i>a </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">TimeCard</font><font face="Times New Roman, Times, Serif" size="3"> object has a </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">Time</font><font face="Times New Roman, Times, Serif" size="3"> object as a subobject (see Figure 16-7).</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>Implementation of the </i></font><i><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">TimeCard</font><font face="Times New Roman, Times, Serif" size="3"> Class</font></i></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">The private data of </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">TimeCard</font><font face="Times New Roman, Times, Serif" size="3"> consists of a long variable named </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">id</font><font face="Times New Roman, Times, Serif" size="3"> and a </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">Time</font><font face="Times New Roman, Times, Serif" size="3"> object named </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">timeStamp</font><font face="Times New Roman, Times, Serif" size="3">. The </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">TimeCard</font><font face="Times New Roman, Times, Serif" size="3"> member functions can manipulate </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">id</font><font face="Times New Roman, Times, Serif" size="3"> by using ordinary built-in operations, but they must manipulate </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">timeStamp</font><font face="Times New Roman, Times, Serif" size="3"> through the member functions defined for the </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">Time</font><font face="Times New Roman, Times, Serif" size="3"> class. For example, you could implement the </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">Print</font><font face="Times New Roman, Times, Serif" size="3"> and </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">Punch</font><font face="Times New Roman, Times, Serif" size="3"> functions as follows:</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">void聽TimeCard::Print()聽const<br />{<br />聽聽聽聽cout聽<<聽ID:聽聽<聽id聽<聽聽Time:聽;<br />聽聽聽聽timeStamp.Write();<br />}<br /><br />void聽TimeCard::Punch(聽/*聽in聽*/聽int聽hours,<br />聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽/*聽in聽*/聽int聽minutes,<br />聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽/*聽in聽*/聽int聽seconds聽)<br />{<br />聽聽聽聽timeStamp.Set(hours,聽minutes,聽seconds);<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">Implementing the class constructors is a bit more complicated to describe. Let's start with an implementation of the first constructor shown in the </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">TimeCard</font><font face="Times New Roman, Times, Serif" size="3"> class declaration:</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_921.html">< previous page</a></td> <td align="center" width="40%" style="background: #EEF3E2"><strong style="color: #2F4F4F; font-size: 120%;">page_922</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_923.html">next page ></a></td> </tr> </table> </body> </html>⌨️ 快捷键说明
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