Dart Essentials

1. Data Type

1.1 Core Data Types

Type	Description	Example
int	Integer (whole number)	int a = 10;
double	Floating-point number	double b = 3.14;
num	Supertype of int and double	num x = 5.5;
String	Text (UTF-16 string)	String s = "Hello";
bool	Boolean (true/false)	bool isOk = true;

1.2 Collection Types

Type	Description	Example
List	Ordered collection	List<int> nums = [1,2,3];
Set	Unordered unique collection	Set<int> s = {1,2,3};
Map	Key-value pairs	Map<String,int> m = {"a":1};

1.3 Special Types

Type	Description	Example
dynamic	Can hold any type	dynamic x = "Hello";
Object	Base class of all types	Object obj = 10;
Object?	Nullable object	Object? obj = null;
Null	Represents null value	Null n = null;

1.4 Function Types

Type	Description	Example
Function	Function as variable	Function f = () {};
Custom Function	Specific function signature	int Function(int,int)

1.5 Advanced Types

Type	Description	Example
Record	Multiple values (tuple-like)	(int, String) r = (1, "A");
Enum	Fixed set of constants	enum Color {red, blue}
typedef	Type alias	typedef MyInt = int;

1.6 Nullable Types

Type	Description	Example
int?	Nullable integer	int? a = null;
String?	Nullable string	String? s;

1.7 Type Keywords

Keyword	Description
var	Type inferred automatically
final	Single assignment
const	Compile-time constant

2. Operator

2.1. Arithmetic Operators

Operator	Name	Description	Example	Result
+	Addition	Adds two values	3 + 6	9
-	Subtraction	Subtracts two values	7 - 5	2
*	Multiplication	Multiplies two values	3 * 2	6
/	Division	Returns double result	7/3	2
~/	Integer Division	Returns integer result	5 ~/ 3	1
%	Modulo	Remainder of division	5 % 3	2

2.2. Increment & Decrement

Operator	Name	Description	Example Code	Result
++a	Pre-increment	Increase value before using it	int a = 5; int b = ++a;	a = 6, b = 6
a++	Post-increment	Use value first, then increase	int a = 5; int b = a++;	a = 6, b = 5
--a	Pre-decrement	Decrease value before using it	int a = 5; int b = --a;	a = 4, b = 4
a--	Post-decrement	Use value first, then decrease	int a = 5; int b = a--;	a = 4, b = 5

2.3. Assignment Operators

Operator	Name	Description	Example
=	Assign	Assign value	a = 10
+=	Add & Assign	a = a + b	a += b
-=	Subtract & Assign	a = a - b	a -= b
*=	Multiply & Assign	a = a * b	a *= b
/=	Divide & Assign	a = a / b	a /= b
~/=	Int Divide Assign	a = a ~/ b	a ~/= b
%=	Modulo Assign	a = a % b	a %= b
??=	Null Assign	Assign if null	a ??= b

2.4. Comparison Operators

Operator	Name	Example
==	Equal	a == b
!=	Not Equal	a != b
>	Greater Than	a > b
<	Less Than	a < b
>=	Greater or Equal	a >= b
<=	Less or Equal	a <= b

2.5. Logical Operators

Operator	Name	Description	Example
&&	AND	True if both true	a && b
||	OR	True if one is true	a || b
!	NOT	Negates condition	!a

2.6. Type Test Operators

Operator	Name	Description	Example
is	Type Test	True if object has type	a is String
is!	Not Type	True if not type	a is! int

2.7. Null-aware Operators

Operator	Name	Description	Example
??	If Null	Return right if left is null	a ?? b
?.	Null-aware Access	Access if not null	a?.length
!	Null Assertion	Force non-null	a!.length

2.8. Cascade Operators

Operator	Name	Description	Example
..	Cascade	Chain multiple calls	obj..a()..b()
?..	Null-aware Cascade	Cascade if not null	obj?..a()

2.9. Other Operators

Operator	Name	Description	Example
[]	Index	Access element	list[0]
[]=	Index Assign	Assign element	list[0] = 1
.	Member Access	Access property	obj.name
?[]	Null-aware Index	Safe index access	list?[0]
...	Spread	Spread elements	[...list]
...?	Null-aware Spread	Spread if not null	[...?list]