Bitcoin Transaction fee/code

Bitcoin Programming 101
#1

Can anyone point me to how the transaction fee is determined in the Bitcoin Core implementation? Basically, I know where to see the block reward, but after the block reward is gone, how would the Tx fee is established in the Core implementation code?

Cheers!

#2

As we mentioned in Bitcoin 101 course the fee is implied as the difference between the inputs and outputs.

#3

THX. I will check the other class too.