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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_720</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_719.html">< previous page</a></td> <td align="center" width="40%" style="background: #EEF3E2"><strong style="color: #2F4F4F; font-size: 120%;">page_720</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_721.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 720</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"><i>Column Processing</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="Courier New, Courier, Mono New, Courier, Mono" size="2">for聽(col聽=聽minCol;聽col聽<聽colLength;聽col++)<br />聽聽聽聽for聽(row聽=聽minRow;聽row聽<聽rowLength;聽row++)<br />聽聽聽聽聽聽聽聽.<br />聽聽聽聽聽聽聽聽.<br />聽聽聽聽聽聽聽聽.聽聽聽聽聽聽聽聽聽聽//聽Whatever聽processing聽is聽required</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="17"></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">Passing Two-Dimensional Arrays as Parameters</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">In Chapter 11, we said that when one-dimensional arrays are declared as formal parameters in a function, the size of the array usually is omitted:</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">void聽SomeFunc(聽/*聽inout聽*/聽float聽list[],<br />聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽/*聽in聽*/聽聽聽聽int聽聽聽size聽聽聽)<br />{<br />聽聽聽聽聽.<br />聽聽聽聽聽.<br />聽聽聽聽聽.<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">If you include a size in the square brackets, the compiler ignores it. As you learned, the base address of the actual parameter (the memory address of the first array element) is passed to the function. The function works for an actual parameter of any size. Because the function cannot know the size of the caller's actual array, we either pass the size as a parameteras in </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">SomeFunc</font><font face="Times New Roman, Times, Serif" size="3"> aboveor use a declared constant if the function always operates on an array of a certain size.</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">When a two-dimensional array is passed as a parameter, again the base address of the actual array is sent to the function. But you cannot leave off the sizes of both of the array dimensions. You can omit the size of the first dimension (the number of rows) but not the second (the number of columns). Here is the reason.</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">In the computer's memory, C++ stores two-dimensional arrays in row order. Thinking of memory as one long line of memory cells, the first row of the array is followed by the second row, which is followed by the third, and so on (see Figure 13-7). To locate </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">table[1][0]</font><font face="Times New Roman, Times, Serif" size="3"> in this figure, a function that receives </font><font face="Courier New, Courier, Mono New, Courier, Mono" size="3">table's</font><font face="Times New Roman, Times, Serif" size="3"> base address must be able to know that there are four elements in each rowthat is, that the table consists of four columns. Therefore, the declaration of a formal parameter must always state the number of columns:</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_719.html">< previous page</a></td> <td align="center" width="40%" style="background: #EEF3E2"><strong style="color: #2F4F4F; font-size: 120%;">page_720</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_721.html">next page ></a></td> </tr> </table> </body> </html>⌨️ 快捷键说明
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