📄 page_66.html
字号:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> <html> <head> <title>page_66</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_65.html">< previous page</a></td> <td align="center" width="40%" style="background: #EEF3E2"><strong style="color: #2F4F4F; font-size: 120%;">page_66</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_67.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 66</font></td></tr></table><table cellpadding="0" cellspacing="0" border="0" width="100%"><tr><td height="12"></td></tr><tr><td><table cellspacing="0" width="362" cellpadding="7"><tr><td valign="top"><font face="Times New Roman, Times, Serif" size="2"><i>Expression</i></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2"><i>Value</i></font></td></tr><tr><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">3聽+聽6</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2">9</font></td></tr><tr><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">3.4聽-聽6.1</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2">-2.7</font></td></tr><tr><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">2聽*聽3</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2">6</font></td></tr><tr><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">8聽/聽2</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2">4</font></td></tr><tr><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">8.0聽/聽2.0</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2">4.0</font></td></tr><tr><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">8聽/聽8</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2">1</font></td></tr><tr><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">8聽/聽9</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2">0</font></td></tr><tr><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">8聽/聽7</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2">1</font></td></tr><tr><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">8聽%聽8</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2">0</font></td></tr><tr><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">8聽%聽9</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2">8</font></td></tr><tr><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">8聽%聽7</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2">1</font></td></tr><tr><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">0聽%聽7</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2">0</font></td></tr><tr><td valign="top"><font face="Times New Roman, Times, Serif" size="2"></font><font face="Courier New, Courier, Mono New, Courier, Mono" size="2">5聽%聽2.3</font><font face="Times New Roman, Times, Serif" size="2"></font></td><td valign="top"><font face="Times New Roman, Times, Serif" size="2">error (both operands must be integers)</font></td></tr></table></td></tr></table><br /><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">Be careful with division and modulus. The expressions </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">7.0聽/聽0.0</font><font face="Times New Roman, Times, Serif" size="3">, </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">7聽/聽0</font><font face="Times New Roman, Times, Serif" size="3">, and </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">7聽%聽0</font><font face="Times New Roman, Times, Serif" size="3"> all produce errors. The computer cannot divide by zero.</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 variables are allowed in expressions, the following are valid assignments:</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">alpha聽=聽num聽+聽6;<br />alpha聽=聽num聽/聽2;<br />num聽=聽alpha聽*聽2;<br />num聽=聽6聽%聽alpha;<br />alpha聽=聽alpha聽+聽1;<br />num聽=聽num聽+聽alpha;</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">Notice that the same variable can appear on both sides of the assignment operator. In the case of</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">num聽=聽num聽+聽alpha;</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 value in </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">num</font><font face="Times New Roman, Times, Serif" size="3"> and the value in </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">alpha</font><font face="Times New Roman, Times, Serif" size="3"> are added together, then the sum of the two values is stored into </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">num</font><font face="Times New Roman, Times, Serif" size="3">, replacing the previous value stored there. This example shows the difference between mathematical equality and assignment. The mathematical equality</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"><img src="9c4dfc83802de207279d50e97b0c8d50.gif" border="0" alt="0066-03.gif" width="136" height="25" /></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">is true only when </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">alpha</font><font face="Times New Roman, Times, Serif" size="3"> equals zero. The assignment statement</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_65.html">< previous page</a></td> <td align="center" width="40%" style="background: #EEF3E2"><strong style="color: #2F4F4F; font-size: 120%;">page_66</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_67.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 + -