What is a variable in Dart?

variables are used to store the value at the memory location. It contains a namespace referring to memory location. Declaration

Variables can be declared in multiple ways

You can use using var keyword or directly use the type without the var keyword Syntax:

type variableName;
var variable=value;

The first one is a type of variable that must be declared with a variable name. Type can be primitive or custom types declared in Dart.

Syntax: Single variable declaration syntax

type variableName;

Multiple variables can be declared with a separator comma(,)

type variableName;

type is a datatype of a variable value to store it.

It can be In built type or custom type

The following are built primitive types.

  • number types: Numerical values such as num, int, double
  • string : String of values
  • bool: a true or false values
  • dynamic:
  • list:
  • map:
  • set:

Here is an example of declaring variables in multiple ways

void main() {
  // declare using var
  var str = "welcome";
  //declare using type
  String str2 = "hello";
}

the first variable is declared and initialized with stringvalue. The Dart compiler checks the right-hand value type, here is a string type, and the variable has inferred this type as a string type.

The second way, declared a variable with String type and assigned it a value

Default value for the variable

variables declared without initialization have a default value of null.

Variable scopes

Each Variable declared in dart has scope and scope is lifetime based on the place of declaration.

There are two types of variable scopes.

  • Global Variable
  • Local Variable