/in/foo.cc: In function 'int main()':
/in/foo.cc:10:9: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
  while (gets(a)
         ^
In file included from /usr/include/c++/5/cstdio:42:0,
                 from /usr/include/c++/5/ext/string_conversions.h:43,
                 from /usr/include/c++/5/bits/basic_string.h:5249,
                 from /usr/include/c++/5/string:52,
                 from /usr/include/c++/5/bits/locale_classes.h:40,
                 from /usr/include/c++/5/bits/ios_base.h:41,
                 from /usr/include/c++/5/ios:42,
                 from /usr/include/c++/5/ostream:38,
                 from /usr/include/c++/5/iostream:39,
                 from /in/foo.cc:1:
/usr/include/stdio.h:638:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^
/in/foo.cc:10:9: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
  while (gets(a)
         ^
In file included from /usr/include/c++/5/cstdio:42:0,
                 from /usr/include/c++/5/ext/string_conversions.h:43,
                 from /usr/include/c++/5/bits/basic_string.h:5249,
                 from /usr/include/c++/5/string:52,
                 from /usr/include/c++/5/bits/locale_classes.h:40,
                 from /usr/include/c++/5/bits/ios_base.h:41,
                 from /usr/include/c++/5/ios:42,
                 from /usr/include/c++/5/ostream:38,
                 from /usr/include/c++/5/iostream:39,
                 from /in/foo.cc:1:
/usr/include/stdio.h:638:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^
/in/foo.cc:10:15: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
  while (gets(a)
               ^
In file included from /usr/include/c++/5/cstdio:42:0,
                 from /usr/include/c++/5/ext/string_conversions.h:43,
                 from /usr/include/c++/5/bits/basic_string.h:5249,
                 from /usr/include/c++/5/string:52,
                 from /usr/include/c++/5/bits/locale_classes.h:40,
                 from /usr/include/c++/5/bits/ios_base.h:41,
                 from /usr/include/c++/5/ios:42,
                 from /usr/include/c++/5/ostream:38,
                 from /usr/include/c++/5/iostream:39,
                 from /in/foo.cc:1:
/usr/include/stdio.h:638:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^
/in/foo.cc:10:15: error: cannot convert 'std::__cxx11::string {aka std::__cxx11::basic_string<char>}' to 'char*' for argument '1' to 'char* gets(char*)'
  while (gets(a)
               ^
/in/foo.cc:11:2: error: expected ')' before '{' token
  {
  ^
/in/foo.cc:17:17: error: expected primary-expression before '[' token
   cout << string[i] << endl;
                 ^