foo.cc: In function ‘int main()’:
foo.cc:7:5: warning: ‘char* gets(char*)’ is deprecated [-Wdeprecated-declarations]
    7 | gets(s);
      | ~~~~^~~
In file included from /nix/gcc-14.2.1.20250322/include/c++/14.2.1.20250322/cstdio:42,
                 from /nix/gcc-14.2.1.20250322/include/c++/14.2.1.20250322/ext/string_conversions.h:45,
                 from /nix/gcc-14.2.1.20250322/include/c++/14.2.1.20250322/bits/basic_string.h:4154,
                 from /nix/gcc-14.2.1.20250322/include/c++/14.2.1.20250322/string:54,
                 from /nix/gcc-14.2.1.20250322/include/c++/14.2.1.20250322/bits/locale_classes.h:40,
                 from /nix/gcc-14.2.1.20250322/include/c++/14.2.1.20250322/bits/ios_base.h:41,
                 from /nix/gcc-14.2.1.20250322/include/c++/14.2.1.20250322/ios:44,
                 from /nix/gcc-14.2.1.20250322/include/c++/14.2.1.20250322/ostream:40,
                 from iostream:41:
/nix/glibc-2.40-66-dev/include/stdio.h:667:14: note: declared here
  667 | extern char *gets (char *__s) __wur __attribute_deprecated__;
      |              ^~~~
foo.cc: In function ‘void DianDao(char*)’:
foo.cc:15:5: warning: statement has no effect [-Wunused-value]
   15 | for(i; s[i]!=0; i++)
      |     ^
/nix/binutils-2.44/bin/ld: /tmp/ccVSSPGd.o: in function `main':
foo.cc:(.text.startup+0xc): warning: the `gets' function is dangerous and should not be used.