Free Pascal supports the Boolean type, with its two pre-defined possible values True and False. These are the only two values that can be assigned to a Boolean type. Of course, any expression that resolves to a boolean value, can also be assigned to a boolean type.
Assuming B to be of type Boolean, the following are valid assignments:
B:=True;
B:=False;
B:=1<>2; { Results in B:=True }
Boolean expressions are also used in conditions.
Remark: In Free Pascal, boolean expressions are always evaluated in such a way that when the result is known, the rest of the expression will no longer be evaluated (Called short-cut evaluation). In the following example, the function Func will never be called, which may have strange side-effects.
... B:=False; A := B and Func;Here Func is a function which returns a Boolean type.
Remark: The wordbool, longbool and bytebool were not supported by Free Pascal until version 0.99.6.