Booleans
To represent boolean values, Dart has a type named bool
. Only twoobjects have type bool: the boolean literals true
and false
,which are both compile-time constants.
Dart’s type safety means that you can’t use code likeif (nonbooleanValue)
orassert (nonbooleanValue)
.Instead, explicitly check for values, like this:
// Check for an empty string.
var fullName = '';
assert(fullName.isEmpty);
// Check for zero.
var hitPoints = 0;
assert(hitPoints <= 0);
// Check for null.
var unicorn;
assert(unicorn == null);
// Check for NaN.
var iMeantToDoThis = 0 / 0;
assert(iMeantToDoThis.isNaN);