Why do IDEs stick to old code after an error?

What is it about IDEs - be it Flash Develop, Flash Builder, Visual Studio or even Eclipse - that makes them stick to the old error even when you delete all the code and start afresh they point out the error that was there previously as though it is there magically invisible all the time..even in your new code.

Its a real bugger for those who don't know the ins and outs of the said IDEs. Once you make an error, that's it! No 开发者_运维知识库matter if you delete all the code that was there and simply make it print some lines on the screen you get "Error this..Error that" or the ominous "Build Failed" without giving any info.

Well if anyone has gone through this newbie stage and now know better please point out if its a feature that these IDEs have and how to overcome this thing.

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Have you tried build clean?

I've seen this from time to time on large builds.

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There were some instances of that problem in old (2007) Eclipse CDT, as illustrated by bug 186619: "[Builder] Clean does not remove error markers".

But for recent CDT versions, the answers remains:

All problem markers are deleted at start of build. This includes clean builds.
This worksforme in current CDT.

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Regarding VS, the only time I've encountered these kinds of issues is when one or more files have become corrupted. If this has happened it often works to delete any .suo and .user files as well as the obj and bin directories.

Otherwise if you still encounter these issues I'd suggest opening a bug on the MS Connect website.

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Flash develop simply shows "Build failed" error, even if your code is correct, if you had made an error previously and you clicked 'stop' in the debug options and then closed the flash debugger player window. Its because, due to some reason I don't understand, its still running in the background and you have to close it via task manager.