How to manipulate the contents of CEdit?

I have a situation with edit control and I need some guidance. The text editor functions normally in most cases but in other cases, depending on the last few characters before typing and based on the characters typed, the last few characters must be replaced with different characters.

The solution that looks obvious to me is to have a character buffer, GetWindowText() just before the contents are changed, add the characters typed into the buffer, manipulate the buffer if necessary and then SetWimdowText().

I know the edit control has its own buffer. So is this the right approach to have my own buffer or are ther开发者_Python百科e ways I can share the buffer with it etc? The editor might not have more than 4MB worth of characters.

I need this to work on Windows 7 and XP, not keen on older ones.I use MFC.

Thanks for your help.

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You don't need your own buffer and indeed it would be dangerous to have one since it will likely get out of synchronisation.

But you don't need to set the entire edit text at once. From the documentation:

Also, if an edit control is multiline, get and set part of the control's text by calling the CEdit member functions GetLine, SetSel, GetSel, and ReplaceSel.

ReplaceSel is what you are looking for I think. Although this text talks about multiline edit controls, SetSel, ReplaceSel etc. work fine with single line edit controls.