📄 page_405.html
字号:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> <html> <head> <title>page_405</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_404.html">< previous page</a></td> <td align="center" width="40%" style="background: #EEF3E2"><strong style="color: #2F4F4F; font-size: 120%;">page_405</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_406.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 405</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">middle of a semester. The amount to be refunded is the total tuition times the remaining fraction of the semester (the number of days remaining divided by the total number of days in the semester). The people who use the program want to be able to enter the dates on which the semester begins and ends and the date of withdrawal, and they want the program to calculate the fraction of the semester that remains.</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">Because each semester begins and ends within one calendar year, we can calculate the number of days in a period by determining the day number of each date and subtracting the starting day number from the ending day number. The day number is the number associated with each day of the year if you count sequentially from January 1. December 31 has the day number 365, except in leap years, when it is 366. For example, if a semester begins on 1/3/97 and ends on 5/17/97, the calculation is 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="Times New Roman, Times, Serif" size="3">The day number of 1/3/97 is 3<br />The day number of 5/17/97 is 137<br />The length of the semester is 137-3+1=135</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">We add 1 to the difference of the days because we count the first day as part of the period.</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 algorithm for calculating the day number for a date is complicated by leap years and by months of different lengths. We could code this algorithm as a void function named </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">ComputeDay</font><font face="Times New Roman, Times, Serif" size="3">. The refund could then be computed by the following code segment.</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">ComputeDay(startMonth,聽startDay,聽startYear,聽start);<br />ComputeDay(lastMonth,聽lastDay,聽lastYear,聽last);<br />ComputeDay(withdrawMonth,聽withdrawDay,聽withdrawYear,聽withdraw);<br />fraction聽=聽float(last聽-聽withdraw聽+聽l)聽/聽float(last聽-聽start聽+聽l);<br />refund聽=聽tuition聽*聽fraction;</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 first three parameters to </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">ComputeDay</font><font face="Times New Roman, Times, Serif" size="3"> are received by the function, and the last one is returned to the caller. Because </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">ComputeDay</font><font face="Times New Roman, Times, Serif" size="3"> returns only one value, we can write it as a value-returning function instead of a void function. Let's look at how the code segment would be written if we had a valuereturning function named </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">Day</font><font face="Times New Roman, Times, Serif" size="3"> that returned the day number of a date in a given year.</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">start聽=聽Day(startMonth,聽startDay,聽startYear);<br />last聽=聽Day(lastMonth,聽lastDay,聽lastYear);<br />withdraw聽=聽Day(withdrawMonth,聽withdrawDay,聽withdrawYear);<br />fraction聽=聽float(last聽-聽withdraw聽+聽1)聽/聽float(last聽-聽start聽+聽1);<br />refund聽=聽tuition聽*聽fraction;</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 version of the code segment is much more intuitive. Because </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">Day</font><font face="Times New Roman, Times, Serif" size="3"> is a value-returning function, you know immediately that all its parame-</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_404.html">< previous page</a></td> <td align="center" width="40%" style="background: #EEF3E2"><strong style="color: #2F4F4F; font-size: 120%;">page_405</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_406.html">next page ></a></td> </tr> </table> </body> </html>⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -