foo.cc: In function 'int main()':
foo.cc:13:2: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
  gets(str1);
  ^~~~
In file included from /usr/include/c++/6/cstdio:42:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:46,
                 from foo.cc:1:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
foo.cc:13:11: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
  gets(str1);
           ^
In file included from /usr/include/c++/6/cstdio:42:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:46,
                 from foo.cc:1:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
foo.cc:14:2: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
  gets(str2);
  ^~~~
In file included from /usr/include/c++/6/cstdio:42:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:46,
                 from foo.cc:1:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
foo.cc:14:11: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
  gets(str2);
           ^
In file included from /usr/include/c++/6/cstdio:42:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:46,
                 from foo.cc:1:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
/tmp/ccElhD9v.o: In function `main':
foo.cc:(.text.startup+0xc): 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)