foo.c: In function 'main':
foo.c:5:5: warning: 'gets' is deprecated [-Wdeprecated-declarations]
     gets(a);
     ^~~~
In file included from foo.c:1:0:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
foo.c:7:14: warning: array subscript has type 'char' [-Wchar-subscripts]
     for(i=0;a[i];++i)
              ^
foo.c:10:18: warning: array subscript has type 'char' [-Wchar-subscripts]
         for(j=i;a[j];j++)
                  ^
foo.c:12:17: warning: array subscript has type 'char' [-Wchar-subscripts]
             if(a[j]==c)
                 ^
foo.c:20:25: warning: array subscript has type 'char' [-Wchar-subscripts]
                 a[j-n]=a[j];
                         ^
/tmp/cc1fV52E.o: In function `main':
foo.c:(.text.startup+0x11): warning: the `gets' function is dangerous and should not be used.

自豪的采用jd5进行评测(github.com/masnn/jd5)