How to get numerical value from 4*4 matrix keypad?

I want to give a specific temperature input to Arduino from 4*4 matrix keypad. But I am not getting those kinds of code on the internet. Most of them taking the inputs as a character. Can anyone give me the code for the numerical input, please?

If the keypad returns a character between ‘0’ and ‘9’ then if you subtract ‘0’ from it you will get the numerical value of the key.

Come back with some code when you get this working as I suspect that there is more to your question.