<p>Does anyone know how to get IntelliSense to work reliably when working in C/C++ projects? It seems to work for about 1 in 10 files. Visual Studio 2005 seems to be a lot better than 2008.</p>

<p>Edit: Whilst not necessarily a solution, the work-around provided here: </p>

<p><a href="https://stackoverflow.com/questions/39474/how-to-get-intellisense-to-reliably-work-in-visual-studio-2008#39590">How to get IntelliSense to reliably work in Visual Studio 2008</a></p>

<p>Is probably the best bet if I want a decent IntelliSense system.</p>

Native C++ intellisense does not work reliably in any version of Visual Studio. I find there are two common problems:
1) Header file paths are not set-up correctly. When you find a type where intellisense is not working, use the IDE to click through each header file to find the one containing the type. (Right click on #include and select Open Document...). If this fails before you get to the file which declares the type then this is your problem. Make sure header file search paths are set-up correctly.
And,
2) The intellisense database is corrupt. This happens ALL The time. You need to close the solution, delete the .ncb file, and then reopen the solution. I posted the macro I use for this in answer to another question
here
.
The preprocessor can also confuse intellisense - so make sure any #defines during build are also available to intellisense. Other than that, I don't know what else can break it. I've not seen any particular issues with forward declarations.