Dart has the usual control structures with no surprises here (refer to control.dart).

The if…else statement (with an optional else) is as follows:

var n = 25;
if (n < 10) {
  print('1 digit number: $n');
} else if (n >=  10 && n < 100){
  print('2+ digit number: $n'); // 2+ digit number: 25
} else {
  print('3 or more digit number: $n');
}

Single-line statements without {} are allowed, but don't mix the two. A simple and short if…else statement can be replaced by a ternary operator (?…:), as shown in the following example code:

num rabbitCount = 16758;
(rabbitCount > 20000) ? print('enough for this year!') : print('breed on!');   // breed on!

If the expression before ? is true, the first statement is executed, else the statement after : is executed. To test whether a variable v refers to a real object, use: if (v != null) { … }.

Testing whether an object v is of type T is done with an if statement: if (v is T).

In this case, we can safely...