Plz explain 7th line of code and hence the output?

Question

C challenge question.plz explain how can we subtract pointers.
https://code.sololearn.com/cAFMEogMZJO3/?ref=app

Answer 1

Pointer points to memory blocks. If you do pointer++, you will point to the next memory block. And if you subtract pointer and pointer++, you will get the difference in memory blocks, which is 1 in this case:

https://stackoverflow.com/questions/3238482/pointer-subtraction-confusion