Update your C compiler for C99 compliance
Joe Marrero commented
+1 No C99 support is ridiculous.
Similar idea was posted here -> http://visualstudio.uservoice.com/forums/121579-visual-studio/suggestions/2089423-c99-support?tracking_code=82d725a3b184701134e10e319ecaf920 but MS don't want to do that. Main priority is C++11.
If huge C devs group could emerge from current MS developers' community, and demand adding equal support for both C and C++, I bet MS could consider this. But at the moment, most of devs don't give a FAQ about that.
Earlier, anti-geekish and anti-opensource, policy of MS created this present ecosystem.
Programmers usually prefer to use C++ than C, or abandon Visual Studio platform in favor of other IDEs, sometimes even change their operating systems.
Spurt is needed, otherwise nothing will change.