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

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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)