How to keep tract of next to act if first to act player folds?

Question

Three handed game with Button SB BB, first to act is Button Calls, SB folds, BB Checks. Now on the flop normally it's SB to act but it's folded, now who's to act next?

The reason I am asking is I am trying to write a poker software, and have trouble keeping track of involved players in the hand and decide who to act next.

To determine the next to act, I've mistakenly reduced the last round actions (flop turn river etc.) starting with all involved players and dropping those that either folded or went all-in, this calculation is wrong because I have to reduce all the rounds, this is inefficient and can be avoided.

Answer 1

In every postflop round, the player on the Small Blind is first to act, then comes the Big Blind and so on... If a player is not in the hand anymore, his turn is "skipped", jumping to the following one. In your case, the small blind is not in the hand, so the big blind would be first to act, then the button.

Preflop is different because, as Clarko commented, posting blinds is considered an "action", so the actual action begins after the big blind

Screw software by the way!