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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_143</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_142.html">< previous page</a></td> <td align="center" width="40%" style="background: #EEF3E2"><strong style="color: #2F4F4F; font-size: 120%;">page_143</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_144.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 143</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">volved in writing interactive programs that has to do with instructions for the user (the person executing your program).</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">To get data into an interactive program, we begin with <i>input prompts,</i> printed messages that explain what the user should enter. Without these messages, the user has no idea what to type into a program. A program also should print out all of the data values typed in so that the user can verify that they were entered correctly. Printing out the input values is called <i>echo printing.</i> Here's a program segment showing the proper use of prompts:</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">cout聽<<聽Enter聽the聽part聽number:聽<<聽endl;聽聽聽聽聽聽聽聽聽聽聽聽聽//聽Prompt<br />cin聽>>聽partNumber;<br />cout聽<<聽Enter聽the聽quantity聽of聽this聽part聽ordered:聽聽聽聽//聽Prompt<br />聽聽聽聽聽<<聽endl;<br />cin聽>>聽quantity;<br />cout聽<<聽Enter聽the聽unit聽price聽for聽this聽part:聽聽聽聽聽聽聽聽聽//聽Prompt<br />聽聽聽聽聽<<聽endl;<br />cin聽>>聽unitPrice;<br />totalPrice聽=聽quantity聽*聽unitPrice;<br />cout聽<<聽Part聽聽<<聽partNumber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Echo聽print<br />聽聽聽聽聽<<聽,聽quantity聽聽<聽quantity<br />聽聽聽聽聽<聽,聽at聽$聽聽<<聽setprecision(2)聽<<聽unitPrice<br />聽聽聽聽聽<聽聽聽each聽<<聽endl;<br />cout聽<<聽totals聽$聽聽<<聽totalPrice聽<<聽endl;</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">And here's the output, with the user's input shown in color:</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">Enter聽the聽part聽number:<br />4671<br />Enter聽the聽quantity聽of聽this聽part聽ordered:<br />10<br />Enter聽the聽unit聽price聽for聽this聽part:<br />27.25<br />Part聽4671,聽quantity聽10,聽at聽$聽27.25聽each<br />totals聽$聽272.50</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 amount of information you put into your prompts depends on who is going to be using a program. If you are writing a program for people who are not familiar with computers, your messages should be more detailed. For example, Type a four-digit part number, then press the key marked RETURN. If the program is going to be used frequently by the same people, you could shorten the prompts: Enter PN. and Enter Qty. If the program is for very experienced users, you can prompt for several values at once and have them type all of the values on one input line:</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">Enter聽PN,聽Qty,聽Unit聽Price:<br />4176聽10聽27.25</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_142.html">< previous page</a></td> <td align="center" width="40%" style="background: #EEF3E2"><strong style="color: #2F4F4F; font-size: 120%;">page_143</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_144.html">next page ></a></td> </tr> </table> </body> </html>⌨️ 快捷键说明
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