Values and variables
on Saturday, 18th of July, 2020
The basic building block of information in your Dart program will be variables. Anytime you're working with data in an app, you can store that data in variables. For example, if you're building a chat application, you can use variables to refer to chat messages or a user.
Variables store references to these values.
One of many ways, and the simplest way, to define a variable in Dart is using the
var key word.
var message = 'Hello, World';
This example creates a variable called
message, and also initializes the variable with a
String value of
Hello, World. Now, you can access that value by referring to the
var message = 'Hello, World'; print(message); // => Hello, World
Inferring the type
Dart is a typed language. The type of the variable
message is String. Dart can infer this
type, so you did't have to explicitly define it as a String. Importantly, this variable must be
a String forever. You cannot re-assign the variable as an integer. If you did want to create a
variable that's more dynamic, you'd use the
dynamic keyword. We'll see examples of that in a later lesson.
dynamic message = 'Hello World';
You can safely re-assign this variable to an integer.
dynamic message = 'Hello, World'; message = 8;
NB: It's rarely advisable to use
dynamic. Your code will benefit from being type safe.
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