I have been reading into this topic and found a bit conflicting information - some say it is mandatory to put a classifier after demonstrative (e.g. zhè), while some say it actually is not mandatory.
For example a question "what's name of this cat", I have seen the following phrase:
zhè māo jiào shén me míng zì? 这猫叫什么名字 ？
so I think, should it not be with zhī?
zhè zhī māo jiào shén me míng zì? 这只猫叫什么名字？
Are both options correct? As I do not know characters much yet, I would be grateful for pinyin in the answers, if possible.