A Boolean expresses a "truth" value, and can therefore be true
or false
. true
and false
are Constants, so can be used in expressions.
For example:
{ a = true } { b = false } { if a } ... { endif } { if a == true } ... { endif } { if a === true } ... { endif }
Note that in the example above, each If
statement checks for the "truthfulness" of variable a
, but the final statement (if a === true
) also checks that a
is explicitly boolean. That is because non-explicit statements perform a conversion to Boolean before making the comparison.
To explicitly convert a value to Boolean, the Boolean typecast operator - ?
- should be used. Some operators, such as the boolean logic NOT operator - !
or not
- also explictly convert a value to Boolean.
When converting to Boolean, the following values are considered to be false
:
false
""
"0"
Every other value is considered to be true
.
The number -1
is considered to be true
, just like any other non-zero number.