Q:

Which one is more efficient: boolean or binary integer?

I have to store a binary value in a variable or an array element, to indicate that an option is enabled or disabled. 
I believe using "Yes" or "No" is less efficient than 1 or 0 (or empty), but I wonder whether there's any difference between 1/0 and TRUE/FALSE, in terms of performance or memory usage or anything else.
Between
$option = 1; # if the option is enabled
$option = 0; # if the option is disabled OR
$option = ""; # if the option is disabled

and
$option = TRUE; # if the option is enabled
$option = FALSE; # if the option is disabled

which way is recommended? Why?
Thanks.

A:

This answer1 suggests that zero, null and empty are equivalent, and this answer2 suggests that 1 and true are equivalent.

