foo.c: In function 'main':
foo.c:8:5: error: expected ';' before 'printf'
     printf("%c%c%c",c,b,a);
     ^~~~~~
foo.c:6:14: warning: variable 'c' set but not used [-Wunused-but-set-variable]
     char a,b,c;
              ^
foo.c:6:12: warning: variable 'b' set but not used [-Wunused-but-set-variable]
     char a,b,c;
            ^
foo.c:6:10: warning: variable 'a' set but not used [-Wunused-but-set-variable]
     char a,b,c;
          ^

自豪的采用jd5进行评测(github.com/masnn/jd5)