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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_498</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_497.html">< previous page</a></td> <td align="center" width="40%" style="background: #EEF3E2"><strong style="color: #2F4F4F; font-size: 120%;">page_498</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_499.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 498</font></td></tr></table><table border="0" cellspacing="0" cellpadding="0"><tr><td rowspan="5"><img src="3e26ecb1b6ac508ae10a0e39d2fb98b2.gif" border="0" width="24" height="1" alt="3e26ecb1b6ac508ae10a0e39d2fb98b2.gif" /></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">聽聽聽聽else<br />聽聽聽聽{<br />聽聽聽聽聽聽聽聽cin聽>>聽int2;<br />聽聽聽聽聽聽聽聽if聽(聽!cin聽||聽int2聽>聽int1)<br />聽聽聽聽聽聽聽聽聽聽聽cout聽<<聽Invalid聽second聽integer.;<br />聽聽聽聽聽聽聽聽else<br />聽聽聽聽聽聽聽聽{<br />聽聽聽聽聽聽聽聽聽聽聽cin聽>>聽int3;<br />聽聽聽聽聽聽聽聽聽聽聽if聽(聽!cin聽||聽int3聽==聽0)<br />聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽cout聽<<聽Invalid聽third聽integer.;<br />聽聽聽聽聽聽聽聽聽聽聽else<br />聽聽聽聽聽聽聽聽聽聽聽{<br />聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽sum聽=聽sum聽+聽(int1聽+聽int2)聽/聽int3;<br />聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽count++;<br />聽聽聽聽聽聽聽聽聽聽聽}<br />聽聽聽聽聽聽聽聽}<br />聽聽聽聽}<br />}聽while聽(cin聽&&聽int1聽>聽0聽&&聽int2聽<=聽int1聽&&聽int3聽!=聽0聽&&<br />聽聽聽聽聽聽聽聽聽count聽<=聽100);</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">12. Write a While loop (and any pre-loop initializations) corresponding to the following loop invariant and loop postcondition.</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"><img src="3e26ecb1b6ac508ae10a0e39d2fb98b2.gif" border="0" width="24" height="1" alt="3e26ecb1b6ac508ae10a0e39d2fb98b2.gif" /></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">//聽Invariant聽(prior聽to聽test):<br />//聽聽聽聽聽prod聽==聽1聽*聽2聽*聽聽*聽(count-1)<br />//聽聽&&聽1聽<=聽count聽<=聽12<br /><br />//聽Postcondition:<br />//聽聽聽聽聽prod聽==聽1聽*聽2聽*聽聽*聽11<br />//聽聽&&聽count聽==聽12</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">13. The following loop is supposed to add the integers 1 through 100, but the loop is wrong (it's off by one). Prove that it is wrong by determining the loop postcondition. (Write the loop invariant for the code as it stands, then use the AND of the loop invariant and the termination condition to find the postcondition.)</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"><img src="3e26ecb1b6ac508ae10a0e39d2fb98b2.gif" border="0" width="24" height="1" alt="3e26ecb1b6ac508ae10a0e39d2fb98b2.gif" /></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">sum聽=聽0;<br />i聽=聽0;<br />while聽(i聽<=聽100)<br />{<br />聽聽聽聽i++;<br />聽聽聽聽sum聽=聽sum聽+聽i;<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"><i>Programming Problems</i></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">1. Develop a top-down design and write a C++ program that inputs a two-letter abbreviation for one of the 50 states and prints out the full name of the state. If the abbreviation isn't valid, the program should print an error message and ask for an abbreviation again. The names of the 50 states and their abbreviations are:</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_497.html">< previous page</a></td> <td align="center" width="40%" style="background: #EEF3E2"><strong style="color: #2F4F4F; font-size: 120%;">page_498</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_499.html">next page ></a></td> </tr> </table> </body> </html>⌨️ 快捷键说明
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