I recently answered a question on what is earnings per share (EPS) and its calculation, you can check through the below link:

However, EPS has at least five different variations and each is used while making a decision about the stocks. These formulae are to help investors to know the stock actual value if it is overvalued or undervalued.

Reported EPS
Ongoing EPS
Carrying value per share
retained earnings per share
Cash EPS.