I used to write “inteface”(it can complie):

but now there are problems:
I used the same ways to write inteface,but can’t fail to complie
Who can help me ?
~~~
I used to write “inteface”(it can complie):

but now there are problems:
~~~
The error message is telling you that an implementation for a non-pure-virtual function Crouch has not been found.
refer to this guide for correctly defining and implementing interface functions: Interfaces in C++ - UE4: Guidebook