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📁 着重介绍基于C++的web编程技术
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<title>3.4 应用程序执行机制</title>
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        <td width="238" bgcolor="#000000" height="20"><p align="right"></font><span style="text-decoration: none"><a href="../../index.htm"><font color="#FFFFFF">电脑报Visual 
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    </center></div><font FACE="Times New Roman" SIZE="4"><b><p ALIGN="CENTER"></b></font><font color="#3973DE" FACE="Times New Roman" SIZE="4">3.4 </font><font SIZE="4" color="#3973DE">应用程序执行机制</font><font FACE="Times New Roman" SIZE="3"></p>
    <b><p ALIGN="JUSTIFY"></b></font><font color="#3973DE" FACE="Times New Roman" SIZE="3">3.4.1 
    WinMain</font><font SIZE="3" color="#3973DE">函数</font><font FACE="Times New Roman" SIZE="3"></p>
    <p ALIGN="JUSTIFY"></font><font SIZE="3">在</font><font FACE="Times New Roman" SIZE="3">DOS</font><font SIZE="3">下，程序的执行是从</font><font FACE="Times New Roman" SIZE="3">main</font><font SIZE="3">函数开始的。在</font><font FACE="Times New Roman" SIZE="3">Windows</font><font SIZE="3">下，对应的函数是</font><font FACE="Times New Roman" SIZE="3">WinMain</font><font SIZE="3">。但是，如果浏览</font><font FACE="Times New Roman" SIZE="3">Hello</font><font SIZE="3">程序的所有的方法和全局函数，是找不到</font><font FACE="Times New Roman" SIZE="3">WinMain</font><font SIZE="3">函数的。</font><font FACE="Times New Roman" SIZE="3">MFC</font><font SIZE="3">考虑到典型的</font><font FACE="Times New Roman" SIZE="3">Windows</font><font SIZE="3">程序需要的大部分初始化工作都是标准化的，因此把</font><font FACE="Times New Roman" SIZE="3">WinMain</font><font SIZE="3">函数隐藏在应用程序的框架中，编译时会自动将该函数链接到可执行文件中。程序员可以重写</font><font FACE="Times New Roman" SIZE="3">WinMain</font><font SIZE="3">函数，但一般不需要这么做。</font><font FACE="Times New Roman" SIZE="3"></p>
    <p ALIGN="JUSTIFY"></font><font SIZE="3">下面的程序清单</font><font FACE="Times New Roman" SIZE="3">3-1</font><font SIZE="3">给出了</font><font FACE="Times New Roman" SIZE="3">WinMain</font><font SIZE="3">函数的代码。其中，</font><font FACE="Times New Roman" SIZE="3">_tWinMain</font><font SIZE="3">函数在</font><font FACE="Times New Roman" SIZE="3">\DevStudio\Vc\Mfc\src\AppModul.cpp</font><font SIZE="3">中定义，它所调用的</font><font FACE="Times New Roman" SIZE="3">AfxWinMain</font><font SIZE="3">函数在同一目录下的</font><font FACE="Times New Roman" SIZE="3">WinMain.cpp</font><font SIZE="3">中定义。名字是</font><font FACE="Times New Roman" SIZE="3">_tWinMain</font><font SIZE="3">函数而不是</font><font FACE="Times New Roman" SIZE="3">WinMain</font><font SIZE="3">，是考虑到对不同字符集的支持，在</font><font FACE="Times New Roman" SIZE="3">tchar.h</font><font SIZE="3">中有</font><font FACE="Times New Roman" SIZE="3">_tWinMain</font><font SIZE="3">的宏定义。在</font><font FACE="Times New Roman" SIZE="3">ANSI</font><font SIZE="3">字符集下编译时，</font><font FACE="Times New Roman" SIZE="3">_tWinMain</font><font SIZE="3">就变成</font><font FACE="Times New Roman" SIZE="3">WinMain</font><font SIZE="3">，在</font><font FACE="Times New Roman" SIZE="3">Unicode</font><font SIZE="3">下编译时，</font><font FACE="Times New Roman" SIZE="3">_tWinMain</font><font SIZE="3">就变成</font><font FACE="Times New Roman" SIZE="3">wWinMain</font><font SIZE="3">。</font><font FACE="Times New Roman" SIZE="3"></p>
    <p ALIGN="JUSTIFY"></font><font SIZE="3"><b>　</p>
    <p ALIGN="JUSTIFY">提示</b>：</font><font FACE="Times New Roman" SIZE="3">Unicode</font><font SIZE="3">是具有固定宽度、统一的文本和字符的编码标准。由于</font><font FACE="Times New Roman" SIZE="3">Unicode</font><font SIZE="3">采用的是</font><font FACE="Times New Roman" SIZE="3">16</font><font SIZE="3">位编码，因此可以包含世界各地的书写系统的字符和技术符号（如中文也在</font><font FACE="Times New Roman" SIZE="3">Unicode</font><font SIZE="3">之中），从而克服了</font><font FACE="Times New Roman" SIZE="3">ASCII</font><font SIZE="3">码在表示多语言文本上的不足之处，扩大了</font><font FACE="Times New Roman" SIZE="3">ASCII</font><font SIZE="3">码</font><font FACE="Times New Roman" SIZE="3">7</font><font SIZE="3">位编码方案的好处。</font><font FACE="Times New Roman" SIZE="3">Unicode</font><font SIZE="3">同等地对待所有的字符，并且在表示各种语言的任何字符时既不需要换码序列（</font><font FACE="Times New Roman" SIZE="3">escape</font><font SIZE="3">）也不需要控制代码。</font><font FACE="Times New Roman" SIZE="3">Win32</font><font SIZE="3">和</font><font FACE="Times New Roman" SIZE="3">Visual C++</font><font SIZE="3">很好的支持</font><font FACE="Times New Roman" SIZE="3">Unicode</font><font SIZE="3">字符集。</font><font FACE="Times New Roman" SIZE="3"></p>
    <p ALIGN="JUSTIFY"></font><b><font SIZE="3">　</p>
    <p ALIGN="JUSTIFY">清单</font><font FACE="Times New Roman" SIZE="3">3-1 _tWinMain</font><font SIZE="3">函数定义</font></b><font FACE="Times New Roman" SIZE="3"></p>
    <p ALIGN="JUSTIFY">// export WinMain to force linkage to this module</p>
    <p ALIGN="JUSTIFY">extern int AFXAPI AfxWinMain(HINSTANCE hInstance, HINSTANCE 
    hPrevInstance,</p>
    <p ALIGN="JUSTIFY">LPTSTR lpCmdLine, int nCmdShow);</p>
    <p ALIGN="JUSTIFY"></font><font SIZE="3">　</font><font FACE="Times New Roman" SIZE="3"></p>
    <p ALIGN="JUSTIFY">#ifdef _MAC</p>
    <p ALIGN="JUSTIFY">extern &quot;C&quot; int PASCAL</p>
    <p ALIGN="JUSTIFY">#else</p>
    <p ALIGN="JUSTIFY">extern &quot;C&quot; int WINAPI</p>
    <p ALIGN="JUSTIFY">#endif</p>
    <p ALIGN="JUSTIFY">_tWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,</p>
    <p ALIGN="JUSTIFY">LPTSTR lpCmdLine, int nCmdShow)</p>
    <p ALIGN="JUSTIFY">{</p>
    <p ALIGN="JUSTIFY">// call shared/exported WinMain</p>
    <p ALIGN="JUSTIFY">return AfxWinMain(hInstance, hPrevInstance, lpCmdLine, nCmdShow);</p>
    <p ALIGN="JUSTIFY">}</p>
    <p ALIGN="JUSTIFY"></font><font SIZE="3">　</font><font FACE="Times New Roman" SIZE="3"></p>
    <p></font><b><font SIZE="3">　</font><font FACE="Times New Roman" SIZE="3"></p>
    <p ALIGN="JUSTIFY">AfxWinMain</font><font SIZE="3">函数定义：</font></b><font FACE="Times New Roman" SIZE="3"></p>
    <p ALIGN="JUSTIFY">/////////////////////////////////////////////////////////////////////////////</p>
    <p ALIGN="JUSTIFY">// Standard WinMain implementation</p>
    <p ALIGN="JUSTIFY">// Can be replaced as long as 'AfxWinInit' is called first</p>
    <p ALIGN="JUSTIFY"></font><font SIZE="3">　</font><font FACE="Times New Roman" SIZE="3"></p>
    <p ALIGN="JUSTIFY">int AFXAPI AfxWinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,</p>
    <p ALIGN="JUSTIFY">LPTSTR lpCmdLine, int nCmdShow)</p>
    <p ALIGN="JUSTIFY">{</p>
    <p ALIGN="JUSTIFY">ASSERT(hPrevInstance == NULL);</p>
    <p ALIGN="JUSTIFY"></font><font SIZE="3">　</font><font FACE="Times New Roman" SIZE="3"></p>
    <p ALIGN="JUSTIFY">int nReturnCode = -1;</p>
    <p ALIGN="JUSTIFY">CWinApp* pApp = AfxGetApp();</p>
    <p ALIGN="JUSTIFY"></font><font SIZE="3">　</font><font FACE="Times New Roman" SIZE="3"></p>
    <p ALIGN="JUSTIFY">// AFX internal initialization</p>
    <p ALIGN="JUSTIFY">if (!AfxWinInit(hInstance, hPrevInstance, lpCmdLine, nCmdShow))</p>
    <p ALIGN="JUSTIFY">goto InitFailure;</p>
    <p ALIGN="JUSTIFY"></font><font SIZE="3">　</font><font FACE="Times New Roman" SIZE="3"></p>
    <p ALIGN="JUSTIFY">// App global initializations (rare)</p>
    <p ALIGN="JUSTIFY">ASSERT_VALID(pApp);</p>
    <p ALIGN="JUSTIFY">if (!pApp-&gt;InitApplication())</p>
    <p ALIGN="JUSTIFY">goto InitFailure;</p>
    <p ALIGN="JUSTIFY">ASSERT_VALID(pApp);</p>
    <p ALIGN="JUSTIFY"></font><font SIZE="3">　</font><font FACE="Times New Roman" SIZE="3"></p>
    <p ALIGN="JUSTIFY">// Perform specific initializations</p>
    <p ALIGN="JUSTIFY">if (!pApp-&gt;InitInstance())</p>
    <p ALIGN="JUSTIFY">{</p>
    <p ALIGN="JUSTIFY">if (pApp-&gt;m_pMainWnd != NULL)</p>
    <p ALIGN="JUSTIFY">{</p>
    <p ALIGN="JUSTIFY">TRACE0(&quot;Warning: Destroying non-NULL m_pMainWnd\n&quot;);</p>
    <p ALIGN="JUSTIFY">pApp-&gt;m_pMainWnd-&gt;DestroyWindow();</p>
    <p ALIGN="JUSTIFY">}</p>
    <p ALIGN="JUSTIFY">nReturnCode = pApp-&gt;ExitInstance();</p>
    <p ALIGN="JUSTIFY">goto InitFailure;</p>
    <p ALIGN="JUSTIFY">}</p>
    <p ALIGN="JUSTIFY">ASSERT_VALID(pApp);</p>
    <p ALIGN="JUSTIFY"></font><font SIZE="3">　</font><font FACE="Times New Roman" SIZE="3"></p>
    <p ALIGN="JUSTIFY">nReturnCode = pApp-&gt;Run();</p>
    <p ALIGN="JUSTIFY">ASSERT_VALID(pApp);</p>
    <p ALIGN="JUSTIFY"></font><font SIZE="3">　</font><font FACE="Times New Roman" SIZE="3"></p>
    <p ALIGN="JUSTIFY">InitFailure:</p>
    <p ALIGN="JUSTIFY">#ifdef _DEBUG</p>
    <p ALIGN="JUSTIFY">// Check for missing AfxLockTempMap calls</p>
    <p ALIGN="JUSTIFY">if (AfxGetModuleThreadState()-&gt;m_nTempMapLock != 0)</p>
    <p ALIGN="JUSTIFY">{</p>
    <p ALIGN="JUSTIFY">TRACE1(&quot;Warning: Temp map lock count non-zero (%ld).\n&quot;,</p>
    <p ALIGN="JUSTIFY">AfxGetModuleThreadState()-&gt;m_nTempMapLock);</p>
    <p ALIGN="JUSTIFY">}</p>
    <p ALIGN="JUSTIFY">AfxLockTempMaps();</p>
    <p ALIGN="JUSTIFY">AfxUnlockTempMaps(-1);</p>
    <p ALIGN="JUSTIFY">#endif</p>
    <p ALIGN="JUSTIFY"></font><font SIZE="3">　</font><font FACE="Times New Roman" SIZE="3"></p>
    <p ALIGN="JUSTIFY">AfxWinTerm();</p>
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