/in/foo.cc: In member function 'void Array::add()':
/in/foo.cc:12:21: warning: unused variable 'i' [-Wunused-variable]
   12 |                 int i = 0;
      |                     ^
/in/foo.cc:13:21: warning: unused variable 't' [-Wunused-variable]
   13 |                 int t;
      |                     ^
/in/foo.cc: In member function 'void Array::_delete(int)':
/in/foo.cc:21:24: warning: converting to non-pointer type 'int' from NULL [-Wconversion-null]
   21 |                 a[n] = NULL;
      |                        ^~~~