Node:Boolean Flags, Next:, Previous:Comments, Up:Words



Boolean Flags

A Boolean flag is cell-sized. A cell with all bits clear represents the flag false and a flag with all bits set represents the flag true. Words that check a flag (for example, IF) will treat a cell that has any bit set as true.

true       -- f         core-ext       ``true''
Constant - f is a cell with all bits set.
false       -- f         core-ext       ``false''
Constant - f is a cell with all bits clear.
on       a-addr --         gforth       ``on''
Set the (value of the) variable at a-addr to true.
off       a-addr --         gforth       ``off''
Set the (value of the) variable at a-addr to false.