Eclipse CDT: Symbol 'cout' could not be resolved
Most likely you have some system-specific include directories missing in your settings which makes it impossible for indexer to correctly parse iostream, thus the errors. Selecting Index -> Search For Unresolved Includes in the context menu of the project will give you the list of unresolved includes which you can search in /usr/include and add containing directories to C++ Include Paths and Symbols in Project Properties.
On my system I had to add /usr/include/c++/4.6/x86_64-linux-gnu for bits/c++config.h to be resolved and a few more directories.
Don't forget to rebuild the index (Index -> Rebuild) after adding include directories.
CDT on OS X Error: Symbol 'cout' could not be resolved
In the end, I downloaded and used Netbeans 8.0.2 C and C++ Development which worked ok straight out of the box.
Eclipse CDT: Symbol 'cout', 'map', 'vector', 'size_t', etc could not be resolved
The .metadata was corrupted. I simply replaced it by a backup.
Still, the origin of the problem remains unknown. As most .metadata files are binary, I cannot investigate the issue any further.
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