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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_726</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_725.html">< previous page</a></td> <td align="center" width="40%" style="background: #EEF3E2"><strong style="color: #2F4F4F; font-size: 120%;">page_726</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_727.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 726</font></td></tr></table><table border="0" cellspacing="0" cellpadding="0" width="100%"><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 align="center"><font face="Times New Roman, Times, Serif" size="3"><img src="b8d68e7029f7aec7741bc4403e362caf.gif" border="0" alt="0726-01.gif" width="257" height="204" /></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" width="100%"><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 align="center"><font face="Times New Roman, Times, Serif" size="2">Figure聽13-9<br />Graphical聽Representation聽of聽Array聽Variable<br /></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">sales</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 </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">item</font><font face="Times New Roman, Times, Serif" size="3"> controls the outer For loop, we are summing each item's sales by </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">month</font><font face="Times New Roman, Times, Serif" size="3"> and </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">store</font><font face="Times New Roman, Times, Serif" size="3">. If we want to find the total sales for each store, we use </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">store</font><font face="Times New Roman, Times, Serif" size="3"> to control the outer For loop, summing its sales by </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">month</font><font face="Times New Roman, Times, Serif" size="3"> and </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">item</font><font face="Times New Roman, Times, Serif" size="3"> with the inner loops.</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">for聽(store聽=聽0;聽store聽<聽NUM_STORES;聽store++)<br />{<br />聽聽聽聽numberSold聽=聽0;<br />聽聽聽聽for聽(item聽=聽0;聽item聽<聽NUM_ITEMS;聽item++)<br />聽聽聽聽聽聽聽聽聽for聽(month聽=聽0;聽month聽<=聽currentMonth;聽month++)<br />聽聽聽聽聽聽聽聽聽聽聽聽聽numberSold聽=聽numberSold聽+聽sales[store][month][item];<br />聽聽聽聽cout聽<<聽Store聽#聽<<聽store聽<<聽聽Sales聽to聽date聽=聽聽<<聽numberSold<br />聽聽聽聽聽聽聽聽聽<<聽聽endl;<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">It takes two loops to access each component in a two-dimensional array; it takes three loops to access each component in a three-dimensional array. The task to be accomplished determines which index controls the outer loop, the middle loop, and the inner loop. If we want to calculate monthly sales by store, </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">month</font><font face="Times New Roman, Times, Serif" size="3"> controls the outer loop and </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">store</font><font face="Times New Roman, Times, Serif" size="3"> controls the middle loop. If we want to calculate monthly sales by item, </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">month</font><font face="Times New Roman, Times, Serif" size="3"> controls the outer loop and </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">item</font><font face="Times New Roman, Times, Serif" size="3"> controls the middle 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="Times New Roman, Times, Serif" size="3">If we want to keep track of the departments that sell each item, we can add a fourth dimension.</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">enum聽Departments聽{A,聽B,聽C,聽D,聽E,聽F,聽G};<br />const聽int聽NUM_DEPTS聽=聽7;<br />typedef聽int聽SalesType[NUM_STORES][12][NUM_ITEMS][NUM_DEPTS];</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">How would we visualize this new structure? Not very easily! Fortunately, we do not have to visualize a structure in order to use it. If we want the</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_725.html">< previous page</a></td> <td align="center" width="40%" style="background: #EEF3E2"><strong style="color: #2F4F4F; font-size: 120%;">page_726</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_727.html">next page ></a></td> </tr> </table> </body> </html>⌨️ 快捷键说明
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