xcode errors with system headers

I'm compiling an application in Xcode and I'm getting a whole load of errors like vprintf, sscanf etc. not declared in /usr/include/gcc/darwin/3.3/c++/cstdio and getchar, fseek etc. not declared in /usr/include/gcc/darwin/3.3/c++/cstdio. These files are system files so there can't be anything wrong with them.

I read that because there are system files that conflict, Xcode does not support recursive folder searches for headers and explicit paths must be used. But what paths do I need to make those errors go away? What's more odd is that there aren't any errors saying any particular header file can't be found but the variables are still undeclared.

The files at fault in the paths above, all do #undef on all the variables (that are according to Xcode undeclared at compile time) first. A comment says things like "Get rid of those macros defined in in lieu of real functions". Then inside namespace std{...}, there are calls saying e.g."
using::fseek;" and it's giving an error for every one like fseek undeclared and Xcode produces about 5000 errors.