I have some pretty pretty C99 codes that have multiple C files are compiled, and when I compile it with Clag 2.7, I get some very strange errors: /usr/include/bits/stdio.h:77: ` Many definitions of 'wizarding' a2test.o: /usr/include/bits/stdio.h: 77: Firstly defined here What is happening is that & lt; Stdio.h & gt; For , the GNU Liby Header file should contain putchar , extern __inline __ , and for any reason in the conflict .o files Putting Definition Then when the linker sees duplicate definitions, then it is bleaching. I suspect a configuration problem: When I use Inclination 2.7 which is with Debian Lane, everything is compiled but for the class I'm reading, the software is red Must be run on Hat Enterprise Linux 5, and my sysadmin has created the stigma 2.7 from the source. (We are not using 2.9 because we are not able to compile the Hello world, and we are not using later versions because we can not find the latest to make it.) I'm look...