/in/foo.cc: In function 'int main()':
/in/foo.cc:9:2: 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 /in/foo.cc:1:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
/in/foo.cc:9:11: 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 /in/foo.cc:1:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
/in/foo.cc:10:2: 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 /in/foo.cc:1:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
/in/foo.cc:10:11: 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 /in/foo.cc:1:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
/in/foo.cc:12:19: warning: NULL used in arithmetic [-Wpointer-arith]
  for(i=0;str1[i]!=NULL;i++);
                   ^~~~
/in/foo.cc:13:19: warning: NULL used in arithmetic [-Wpointer-arith]
  for(j=0;str2[j]!=NULL;j++);
                   ^~~~
/tmp/ccKuWcxM.o: In function `main':
foo.cc:(.text.startup+0x18): warning: the `gets' function is dangerous and should not be used.