What is a variable in Dart?
variables are used to store the value at the memory location. It contains namespace refering to memory location. Declaration
Variables can be declared multiple ways
You can use using var
keyword or directly use type without var keyword
Syntax:
type variableName;
var variable=value;
First one, is an type of an variable must be declare with variablename. Type can be primitive or custom types declared in Dart.
Syntax: Single variable declaration syntax
type variableName;
Multiple variables can be declared with separator comma(,)
type variableName;
type
is an datatype of a variable value to store it.
It can be In built type or custom type
Following are built primitive types.
- number types: Numerical values such as num,int,double
- string : String of values
- bool: a true of false values
- dynamic:
- list:
- map:
- set:
Here is an example for declare variables in multiple ways
void main() {
// declare using var
var str = "welcome";
//declare using type
String str2 = "hello";
}
first variable is declare and initialized with stringvalue. Dart compiler checks the right hand value type, here is string type, variable is infer this type as a string type.
Second way, declared a variable with String type and assigned with a value
Default value for variable
variables declared without initialized has a default value of null.
Variable scopes
Each Variable declared in dart has scope and scope is lifetime based on place of declaration.
There are two types of variables scopes
- Global Variable
- Local Variable