foo.cc: In function 'int main()':
foo.cc:12:2: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
  gets(a);
  ^~~~
In file included from foo.cc:1:0:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
foo.cc:12:8: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
  gets(a);
        ^
In file included from foo.cc:1:0:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
foo.cc: In function 'void sc(char*, char)':
foo.cc:20:8: warning: unused variable 'a' [-Wunused-variable]
  int i,a,b,n;
        ^
foo.cc:20:10: warning: unused variable 'b' [-Wunused-variable]
  int i,a,b,n;
          ^
/tmp/ccDti967.o: In function `main':
foo.cc:(.text.startup+0xe): 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)