so i want to make a code, that creates a binary tree, that holds data, for example ints like 1,6,2,10,8 and on pop i get the biggest number, and after that it gets deleted from the tree, and on push i can insert a new element. And this should be in a template so i can easy change the data type i want to hold in the tree. Now i got the tree so far, without template it is working fine thought, i can add items, and i can print them, but when i try to put it in a template, i get the following error: use of class template requires template argument list . What could be the problem? Maybe i am doing it totally wrong. Any suggestions are welcome.