would it be simpler to do this input validation if the word was a string object?
Well, it's your code. A char array is fine, but with c and c++ is is advisable to initialise your variables first. When you declare a char array either on the stack or heap (i.e. new char[...] ) you must add sufficient room for the null terminating character and then you won't go far wrong.
If I declare a char array on the stack I normally do: