Oh I have just found an important thing. There is a "gsl_block__block_source.c" file. When I compile this on both comandline and codeBlock, I get erros (like unknown type name 'size_t'). After that, I open makefile and see file's name does not exist in makefile. However, There is a "gsl_block__block.c" file. This is compiled and does not get errors. Moreover, "gsl_block__block.c" includes "gsl_block__block_source.c". Why does it happen?