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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_919</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_918.html">< previous page</a></td> <td align="center" width="40%" style="background: #EEF3E2"><strong style="color: #2F4F4F; font-size: 120%;">page_919</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_920.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 919</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">Figure 16-6 (continued)</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ExtTime::Write()聽const<br /><br />//聽Postcondition:<br />//聽聽聽聽聽Time聽has聽been聽output聽in聽the聽form聽HH:MM:SS聽ZZZ<br />//聽聽聽聽聽where聽ZZZ聽is聽the聽time聽zone<br /><br />{<br />聽聽聽聽static聽char聽zoneString[8][4]聽=<br />聽聽聽聽{<br />聽聽聽聽聽聽聽聽EST,聽CST,聽MST,聽PST,聽EDT,聽CDT,聽MDT,聽PDT<br />聽聽聽聽};<br /><br />聽聽聽聽Time::Write();<br />聽聽聽聽cout聽<<聽聽聽<聽zoneString[zone];<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 the first constructor in Figure 16-6, notice the syntax by which a constructor passes parameters to its base class constructor:</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">ExtTime::ExtTime(聽/*聽in聽*/聽int聽聽聽聽聽聽initHrs,<br />聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽/*聽in聽*/聽int聽聽聽聽聽聽initMins,<br />聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽/*聽in聽*/聽int聽聽聽聽聽聽initSecs,<br />聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽/*聽in聽*/聽ZoneType聽initZone聽)<br /><br />聽聽聽聽:聽Time聽(initHrs,聽initMins,聽initSecs)聽聽</font><font face="Symbol" size="2">录</font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">聽聽Constructor聽initializer<br /><br />{<br />聽聽聽聽zone聽=聽initZone;<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">After the parameter list to the </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">ExtTime</font><font face="Times New Roman, Times, Serif" size="3"> constructor (but before its body), you insert what is called a <i>constructor initializer</i>a colon and then the name of the base class along with the actual parameters to <i>its</i> constructor. When an </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">ExtTime</font><font face="Times New Roman, Times, Serif" size="3"> object is created with a declaration such as</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">ExtTime聽time1(8,聽35,聽0,聽PST);</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">the </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">ExtTime</font><font face="Times New Roman, Times, Serif" size="3"> constructor receives four parameters. The first three are simply passed along to 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 constructor by means of the constructor initializer. After 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 constructor has executed (creating the base class subobject as shown in Figure 16-5), the body of the </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">ExtTime</font><font face="Times New Roman, Times, Serif" size="3"> constructor executes, setting </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">zone</font><font face="Times New Roman, Times, Serif" size="3"> equal to the fourth parameter.</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">The second constructor in Figure 16-6 (the default constructor) does not need a constructor initializer; there are no parameters to pass to the base</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_918.html">< previous page</a></td> <td align="center" width="40%" style="background: #EEF3E2"><strong style="color: #2F4F4F; font-size: 120%;">page_919</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_920.html">next page ></a></td> </tr> </table> </body> </html>⌨️ 快捷键说明
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