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  • How do I convert a CString to a char*


    <P>First, be sure you actually need a <CODE>char*</CODE> (non-constant pointer, or
    <CODE>LPTSTR</CODE>). If you need a <CODE>const
    char*</CODE> (or <CODE>LPCTSTR</CODE>), then
    <CODE>CString</CODE> has a conversion function that will be called automatically
    if you pass a <CODE>CString</CODE> to a function expecting an
    <CODE>LPCTSTR</CODE>. For example:</P><PRE>void f ( LPCTSTR somestring )
    {
      cout << somestring << endl;
    }

    main()
    {
    CString str = "bonjour";

      f ( str );  // OK - calls CString::operator LPCTSTR() to convert
    }</PRE>
    <P>The remainder of this FAQ deals with obtaining a non-constant pointer to the
    string.</P>
    <P>Because a <CODE>CString</CODE> object manages the character array, you must
    explicitly tell the <CODE>CString</CODE> that you want to get a non-constant
    pointer to the string. Call <CODE>GetBuffer()</CODE> to get a <CODE>char*</CODE> to the string, and then call
    <CODE>ReleaseBuffer()</CODE> when you no longer need that pointer. Calling
    <CODE>ReleaseBuffer()</CODE> tells the <CODE>CString</CODE> that it can resume
    managing the character array.</P><PRE>CString str = "some string";
    LPTSTR  pch;

      pch = str.GetBuffer(0);

      // use pch here...

      // When you're done using pch, give the CString control
      // of the buffer again.
      str.ReleaseBuffer();</PRE>
    <P>After calling <CODE>GetBuffer()</CODE>, you may modify the contents of the
    string through <CODE>pch</CODE>, although you can't make the string longer since
    that would overrun the array. If you do modify the string, you must not call any
    <CODE>CString</CODE> methods before the call to <CODE>ReleaseBuffer()</CODE>,
    since <CODE>CString</CODE> methods may reallocate and move the array, which
    would render <CODE>pch</CODE> invalid. After you call
    <CODE>ReleaseBuffer()</CODE>, you must not use <CODE>pch</CODE> any more, again
    because the <CODE>CString</CODE> may reallocate and move the character
    array.</P>
    <P>If you want to create a larger buffer for the string, for example if you are
    going to pass it to an API that returns a filename, you can do so by passing the
    desired length to <CODE>GetBuffer()</CODE>:</P><PRE>CString sFilename;
    LPTSTR  pch;

      // Get a non-const pointer and set the buffer size.
      pch = sFilename.GetBuffer ( MAX_PATH );

      // Pass the buffer to an API that writes to it.
      GetModuleFileName ( NULL, pch, MAX_PATH );

      // Return control of the array to the CString object.
      sFilename.RelaseBuffer();</PRE>

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  • 原文地址:https://www.cnblogs.com/cy163/p/533021.html
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