xCode command-line > foundation problem

I'm trying开发者_运维技巧 to set up a command-line > foundation "hello world" project. (as written in the book 'learning objective C for mac') ...When I select 'build & run' with the default settings for this project I get 4 errors, without modifying any code!?

errors:

stdarg.h: no such file or directory
float.h: no such file or directory
xmmintrin.h: no such file or directory
expected specifier-qualifier-list

Solved by Apple Support!

Project was running under 10.4 SDK instead of 10.6 SDK. (Changed this by selecting the Project title in the left pane and then the 'info' option)