Everything you can place in a variable is an object, and everyobject is an instance of a class. Even numbers, functions, and are objects. All objects inherit from the class.
Although Dart is strongly typed, type annotations are optionalbecause Dart can infer types. In the code above,
number
is inferred to be of typeint
. When you want to explicitly saythat no type is expected,use the special typedynamic
.Dart supports top-level functions (such as
main()
), as well asfunctions tied to a class or object (static and instancemethods, respectively). You can also create functions withinfunctions (nested or local functions).Similarly, Dart supports top-level variables, as well as variablestied to a class or object (static and instance variables). Instancevariables are sometimes known as fields or properties.
Identifiers can start with a letter or underscore (_), followed by anycombination of those characters plus digits.
Dart has both expressions (which have runtime values) andstatements (which don’t).For example, the
condition ? expr1 : expr2
has a value ofexpr1
or .Compare that to an if-else statement, which has no value.A statement often contains one or more expressions,but an expression can’t directly contain a statement.