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copied!<p>CString has lots of internal tricks which make it look like a normal string when passed e.g. to <code>printf</code> functions, despite actually being a class - <strong>without having to cast it to <code>LPCTSTR</code> in the argument list, e.g., in the case of <code>varargs</code> (<code>...</code>) in e.g. a <code>printf</code></strong>. Thus trying to understand a single individual trick or function in the CString implementation is bad news. (The data function is an internal function which gets the 'real' buffer associated with the string.)</p> <p>There's a book, MFC Internals that goes into it, and IIRC the Blaszczak book might touch it.</p> <p>EDIT: As for what the expression actually translates to in terms of raw C++:-</p> <pre><code>TCHAR* data() { return (TCHAR*)(&this[1]); }; </code></pre> <p>this says "pretend you're actually the first entry in an array of items allocated together. Now, the second item isnt actually a <code>CString</code>, it's a normal NUL terminated buffer of either Unicode or normal characters - i.e., an LPTSTR".</p> <p>Another way of expressing the same thing is:</p> <pre><code>TCHAR* data() { return (TCHAR*)(this + 1); }; </code></pre> <p>When you add 1 to a pointer to T, you actually add 1* sizeof T in terms of a raw memory address. So if one has a CString located at 0x00000010 with sizeof(CString) = 4, data will return a pointer to a NUL terminated array of chars buffer starting at 0x00000014</p> <p>But just understanding this one thing out of context isnt necessarily a good idea.</p> <p>Why do you <em>need</em> to know?</p>

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