/in/foo.cc: In function 'int main()':
/in/foo.cc:12:13: error: invalid conversion from 'int' to 'void*' [-fpermissive]
  qsort(1,n+1);
             ^
/in/foo.cc:12:13: error: too few arguments to function 'void qsort(void*, size_t, size_t, __compar_fn_t)'
In file included from /usr/include/c++/6/cstdlib:75:0,
                 from /usr/include/c++/6/ext/string_conversions.h:41,
                 from /usr/include/c++/6/bits/basic_string.h:5417,
                 from /usr/include/c++/6/string:52,
                 from /usr/include/c++/6/bits/locale_classes.h:40,
                 from /usr/include/c++/6/bits/ios_base.h:41,
                 from /usr/include/c++/6/ios:42,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/stdlib.h:725:13: note: declared here
 extern void qsort (void *__base, size_t __nmemb, size_t __size,
             ^~~~~