chap2_3.htm

着重介绍基于C++的web编程技术

        <td WIDTH="30%"><font FACE="Times New Roman" SIZE="3">f</font></td>
        <td WIDTH="70%"><font FACE="Times New Roman" SIZE="3">BOOL</font></td>
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        <td WIDTH="30%"><font FACE="Times New Roman" SIZE="3">w</font></td>
        <td WIDTH="70%"><font SIZE="3">字</font><font FACE="Times New Roman" SIZE="3">(WORD</font><font SIZE="3">，无符号短整数</font><font FACE="Times New Roman" SIZE="3">)</font></td>
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        <td WIDTH="30%"><font FACE="Times New Roman" SIZE="3">l</font></td>
        <td WIDTH="70%"><font SIZE="3">长整数</font><font FACE="Times New Roman" SIZE="3">(long)</font></td>
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        <td WIDTH="30%"><font FACE="Times New Roman" SIZE="3">h</font></td>
        <td WIDTH="70%"><font FACE="Times New Roman" SIZE="3">HANDLE</font><font SIZE="3">（无符号</font><font FACE="Times New Roman" SIZE="3">int</font><font SIZE="3">）</font></td>
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        <td WIDTH="30%"><font FACE="Times New Roman" SIZE="3">m_</font></td>
        <td WIDTH="70%"><font SIZE="3">类成员变量</font></td>
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        <td WIDTH="30%"><font FACE="Times New Roman" SIZE="3">fn</font></td>
        <td WIDTH="70%"><font SIZE="3">函数</font><font FACE="Times New Roman" SIZE="3">(function)</font></td>
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        <td WIDTH="30%"><font FACE="Times New Roman" SIZE="3">dw</font></td>
        <td WIDTH="70%"><font SIZE="3">双字</font><font FACE="Times New Roman" SIZE="3">(DWORD</font><font SIZE="3">，无符号长整数</font><font FACE="Times New Roman" SIZE="3">)</font></td>
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    <p><font SIZE="3">　</font><font FACE="Times New Roman" SIZE="3"></p>
    <p>2.</font><font SIZE="3">在标识符内，前缀以后就是一个或者多个第一个字母大写的单词，这些单词清楚地指出了源代码内那个对象的用途。比如，</font><font FACE="Times New Roman" SIZE="3">m_szStudentName</font><font SIZE="3">表示一个学生名字的类成员变量，数据类型是字符串型。<b></p>
    <p>从</font><font FACE="Times New Roman" SIZE="3">16</font><font SIZE="3">位的</font><font FACE="Times New Roman" SIZE="3">Win16 API</font><font SIZE="3">迁移到</font><font FACE="Times New Roman" SIZE="3">Win32 API</font><font SIZE="3">注意点</font></b><font FACE="Times New Roman" SIZE="3"></p>
    <p></font><font SIZE="3">　</font><font FACE="Times New Roman" SIZE="3"></p>
    <p>1.</font><font SIZE="3">数据类型字长的变化：</font><font FACE="Times New Roman" SIZE="3"></p>
    <p></font><font SIZE="3">我们编写一个小程序来说明</font><font FACE="Times New Roman" SIZE="3">Win32</font><font SIZE="3">下的常见数据类型的字长：</font><font FACE="Times New Roman" SIZE="3"></p>
    <p>#include&lt;windows.h&gt;</p>
    <p>#include&lt;stdio.h&gt;</p>
    <p>void main(void)</p>
    <p>{</p>
    <p>printf(&quot;sizeof(int) is %d\n&quot;,sizeof(int));</p>
    <p>printf(&quot;sizeof(BYTE) is %d\n&quot;,sizeof(BYTE));</p>
    <p>printf(&quot;sizeof(WORD) is %d\n&quot;,sizeof(WORD));</p>
    <p>printf(&quot;sizeof(DWORD) is %d\n&quot;,sizeof(DWORD));</p>
    <p>printf(&quot;sizeof(LONG) is %d\n&quot;,sizeof(LONG));</p>
    <p>printf(&quot;sizeof(PVOID) is %d\n&quot;,sizeof(PVOID));</p>
    <p>printf(&quot;sizeof(LPVOID) is %d\n&quot;,sizeof(LPVOID));</p>
    <p>}</p>
    <p></font><font SIZE="3">使用</font><font FACE="Times New Roman" SIZE="3">Visual C++</font><font SIZE="3">编译运行该程序，输出结果如下：</font><font FACE="Times New Roman" SIZE="3"></p>
    <p>sizeof(int) is 4</p>
    <p>sizeof(BYTE) is 1</p>
    <p>sizeof(WORD) is 2</p>
    <p>sizeof(DWORD) is 4</p>
    <p>sizeof(LONG) is 4</p>
    <p>sizeof(PVOID) is 4</p>
    <p>sizeof(LPVOID) is 4</p>
    <p ALIGN="JUSTIFY"></font><font SIZE="3">从上面的输出结果我们看到：整数类型字长已经同长整数相同，</font><font FACE="Times New Roman" SIZE="3">PVOID</font><font SIZE="3">近指针和</font><font FACE="Times New Roman" SIZE="3">LPVOID</font><font SIZE="3">远指针长度也相同。在编程过程中，我们要注意这些变化，凡是设计字长的问题最好还是采用可以移植的</font><font FACE="Times New Roman" SIZE="3">sizeof</font><font SIZE="3">操作符来做。</font><font FACE="Times New Roman" SIZE="3"></p>
    <p>2.</font><font SIZE="3">内存模式变化：</font><font FACE="Times New Roman" SIZE="3"></p>
    <p></font><font SIZE="3">在</font><font FACE="Times New Roman" SIZE="3">Win32</font><font SIZE="3">平台下，不再有微模式、紧凑模式、中模式、大模式、巨模式、自定义内存模式之分，也不再有</font><font FACE="Times New Roman" SIZE="3">64KB</font><font SIZE="3">代码段和数据段的限制。只有一种内存模式，</font><font FACE="Times New Roman" SIZE="3">Win32</font><font SIZE="3">下的地址和代码均在线性寻址的</font><font FACE="Times New Roman" SIZE="3">2GB</font><font SIZE="3">的</font><font FACE="Times New Roman" SIZE="3">32</font><font SIZE="3">位内存空间中。当然，编程时还是要考虑到实际内存限制的。</font><font FACE="Times New Roman" SIZE="3"></p>
    <p>3.</font><font SIZE="3">类型修饰符：</font><font FACE="Times New Roman" SIZE="3"></p>
    <p></font><font SIZE="3">在</font><font FACE="Times New Roman" SIZE="3">Win32</font><font SIZE="3">下，不再有远指针、近指针、巨型指针之分，三种指针类型完全相同。</font><font FACE="Times New Roman" SIZE="3">32</font><font SIZE="3">位的编译器会忽略所有的</font><font FACE="Times New Roman" SIZE="3">_near</font><font SIZE="3">、</font><font FACE="Times New Roman" SIZE="3">_far</font><font SIZE="3">、</font><font FACE="Times New Roman" SIZE="3">_huge</font><font SIZE="3">关键字并一视同仁来处理。在</font><font FACE="Times New Roman" SIZE="3">Win32</font><font SIZE="3">中，象</font><font FACE="Times New Roman" SIZE="3">LPSTR</font><font SIZE="3">和</font><font FACE="Times New Roman" SIZE="3">PSTR</font><font SIZE="3">这种类型是等价的。</font><font FACE="Times New Roman" SIZE="3"></p>
    <p>4.</font><font SIZE="3">函数的变化：</font><font FACE="Times New Roman" SIZE="3"></p>
    <p>Win32API</font><font SIZE="3">设计时尽可能保证与</font><font FACE="Times New Roman" SIZE="3">Win16API</font><font SIZE="3">兼容，但是仍然对一些函数作了修改。比如在</font><font FACE="Times New Roman" SIZE="3">Win16</font><font SIZE="3">下的</font><font FACE="Times New Roman" SIZE="3">MoveTo</font><font SIZE="3">在</font><font FACE="Times New Roman" SIZE="3">Win32</font><font SIZE="3">下为</font><font FACE="Times New Roman" SIZE="3">MoveToEx</font><font SIZE="3">。如果在编译程序时某个</font><font FACE="Times New Roman" SIZE="3">API</font><font SIZE="3">函数没找到，试着在这个函数名后面加上</font><font FACE="Times New Roman" SIZE="3">Ex</font><font SIZE="3">，</font><font FACE="Times New Roman" SIZE="3">Ex</font><font SIZE="3">表示它是</font><font FACE="Times New Roman" SIZE="3">Win16</font><font SIZE="3">的扩展。 </font><font FACE="Times New Roman" SIZE="3"></p>
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    <p align="center"></font><font size="2" color="#000000">本教程由<a href="http://vcdynasty.yeah.net">Visual C++王朝（Where programmers come together）</a>协助制作<br>
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