Need help in matrix keypad coding

[Probotics]

Ah gotcha. So the column is switched to output, then the rows (which are 4 bits over) are examined to see if that row is linked to the column. Thanks - I don't know how I missed it now that I see it. This should help with a keypad with a different number of buttons I've been working on.

[Probotics]

So I remember now why I was having trouble following this. The value of the D port is 0. When set to output it draws the input port low. I didn't realize you had to have pull up resistors in the keypad circuit to keep the input port high whenever not being pulled low. The original circuit using this code that I saw had weak pull up resistors enabled and no external resistors, but the port I was using did not have weak pull up resistors associated with it.