subject_55330.htm

vc

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序号：55330 发表者：qvb 发表日期：2003-10-09 00:21:48
<br>主题：关于变量问题
<br>内容：为何我在CSampleMenuApp类中的定义了public一个变量无法在CSampleMenuView中使用？<BR>哪位大哥解释一下？<BR>编译时总说是末定义<BR>ex:<BR>class CSampleMenuApp : public CWinApp<BR>{<BR>public:<BR>&nbsp;&nbsp;&nbsp;&nbsp;int m_nColor;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;CSampleMenuApp();<BR>...<BR>}<BR>void CSampleMenuView::OnAddDrawing() <BR>{<BR>&nbsp;&nbsp;&nbsp;&nbsp;// TODO: Add your command handler code here<BR>&nbsp;&nbsp;&nbsp;&nbsp;m_nColor=GRAY_BRUSH;<BR>&nbsp;&nbsp;&nbsp;&nbsp; Invalidate(TRUE);<BR>}<BR>void CSampleMenuView::OnDraw(CDC* pDC)<BR>{<BR>&nbsp;&nbsp;&nbsp;&nbsp;CSampleMenuDoc* pDoc = GetDocument();<BR>&nbsp;&nbsp;&nbsp;&nbsp;ASSERT_VALID(pDoc);<BR>&nbsp;&nbsp;&nbsp;&nbsp;// TODO: add draw code for native data here<BR>&nbsp;&nbsp;&nbsp;&nbsp; pDC-&gt;SelectStockObject(m_nColor);<BR>&nbsp;&nbsp;&nbsp;&nbsp;pDC-&gt;Ellipse(CRect(0,0,200,200));<BR><BR>}
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<font color=red>答案被接受</font><br>回复者：ohye212 回复日期：2003-10-09 09:15:14
<br>内容：extern CSampleMenuApp&nbsp;&nbsp;theApp ;///////////////<BR><BR><BR>class CSampleMenuApp : public CWinApp<BR>{<BR>public:<BR>&nbsp;&nbsp;&nbsp;&nbsp;int m_nColor;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;CSampleMenuApp();<BR>...<BR>}<BR>void CSampleMenuView::OnAddDrawing() <BR>{<BR>&nbsp;&nbsp;&nbsp;&nbsp;// TODO: Add your command handler code here<BR>&nbsp;&nbsp;&nbsp;&nbsp;m_nColor=GRAY_BRUSH;<BR>&nbsp;&nbsp;&nbsp;&nbsp; Invalidate(TRUE);<BR>}<BR>void CSampleMenuView::OnDraw(CDC* pDC)<BR>{<BR>&nbsp;&nbsp;&nbsp;&nbsp;CSampleMenuDoc* pDoc = GetDocument();<BR>&nbsp;&nbsp;&nbsp;&nbsp;ASSERT_VALID(pDoc);<BR>&nbsp;&nbsp;&nbsp;&nbsp;// TODO: add draw code for native data here<BR>&nbsp;&nbsp;&nbsp;&nbsp; pDC-&gt;SelectStockObject(theApp.m_nColor);////////////////change<BR>&nbsp;&nbsp;&nbsp;&nbsp;pDC-&gt;Ellipse(CRect(0,0,200,200));<BR><BR>} 
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回复者：CDMA2000 回复日期：2003-10-09 09:19:14
<br>内容：一个类中定义的public变量当然不能直接在另外一个类中使用啊，你要通过那个类的类对象去访问，在你的代码中，你应该这样:<BR>((CSampleMenuApp*)AfxGetApp())-&gt;m_nColor=GRAY_BRUSH;<BR><BR>你好像了解C++的语法不多吧，好好看看基础的东西了<BR>
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回复者：qvb 回复日期：2003-10-09 10:03:50
<br>内容：多谢两位大哥指点，小弟刚开始学vc很多不懂<BR>我是在一本书上抄的程序，没想到有问题。<BR>我还以为在app类包含了view类，看来理解有错误，见笑了！！
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