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Summary - Data types

Combine int, double, String and bool to write a calculation card.

Summary - Data types

In this group you learned Dart's basic data types: int (integer), double (decimal), String (text), bool (boolean) and dynamic (flexible).

You also saw type inference with var and runtime type checks with the is operator. We will practice with two small tasks.

In later lessons we will use these types in function parameters, collections and class fields. The foundation is laid here.

Practice Calculation card

Inside void main() declare int quantity = 3, double price = 9.99, String name = 'Pen'. Print all three with print.

Starter code

main.dart
// Declare variables and print them

Sample solution

main.dart
void main() {
  int quantity = 3;
  double price = 9.99;
  String name = 'Pen';
  print(quantity);
  print(price);
  print(name);
}

Expected output

3
9.99
Pen

Practice Final calculation card

Inside void main() declare an int, a double and a String for a product. Set values to 5, 12.5 and Notebook. Print with print.

Starter code

main.dart
// Complete the program

Sample solution

main.dart
void main() {
  int quantity = 5;
  double price = 12.5;
  String name = 'Notebook';
  print(quantity);
  print(price);
  print(name);
}

Expected output

5
12.5
Notebook

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 Which type fits a product price?

  • double Correct answer
  • int
  • String
  • bool

Explanation: Price is decimal; double fits.

2 Text type

Question 
____ name = 'Alex';
Answer 
String name = 'Alex';

Explanation: Text is stored in this type.

3 Match all types

Term Meaning
int Integer
double Floating-point
String Text
bool Boolean

All lessons in Beginner

1 Dart basics

  1. What is Dart?
  2. Your first program
  3. dart run
  4. Comments
  5. String interpolation
  6. Summary - Dart basics

2 Variables

  1. var and type
  2. final
  3. const
  4. late
  5. Null safety
  6. Summary - Variables

3 Data types

  1. Integer types
  2. Floating-point types
  3. bool and String
  4. Type inference
  5. dynamic
  6. Summary - Data types

4 Project: Calculator

  1. Project design
  2. Add and subtract
  3. Multiply and divide
  4. Error handling
  5. Putting it together

5 Operators

  1. Arithmetic operators
  2. Assignment operators
  3. Comparison operators
  4. Logical operators
  5. Null-aware operators
  6. Summary - Operators

6 Strings

  1. Creating strings
  2. String interpolation
  3. length and methods
  4. substring
  5. contains and indexOf
  6. Summary - Strings

7 Conditionals

  1. The if statement
  2. else and else if
  3. switch
  4. Pattern matching
  5. Ternary
  6. Summary - Conditionals

8 Loops

  1. The for loop
  2. The while loop
  3. The do-while loop
  4. for-in
  5. break and continue
  6. Summary - Loops

9 Project: Shopping cart

  1. Cart design
  2. Adding items
  3. Calculating totals
  4. Listing the cart
  5. Putting it together

10 Lists

  1. Creating lists
  2. List access
  3. add and remove
  4. length and contains
  5. List methods
  6. Summary - Lists

11 Sets and Maps

  1. Set
  2. Set operations
  3. Map
  4. Map operations
  5. Map iteration
  6. Summary - Sets and Maps

12 Functions

  1. Defining functions
  2. Return values
  3. Arrow functions
  4. Optional parameters
  5. First-class functions
  6. Summary - Functions

13 Null safety in depth

  1. Nullable types
  2. Null-aware operators
  3. The ! operator
  4. late
  5. Null check
  6. Summary - Null safety

14 Class basics

  1. class
  2. Constructor
  3. Instance variables
  4. Methods
  5. this
  6. Summary - Class basics

15 Project: To-do CLI

  1. Task model
  2. Adding tasks
  3. Listing tasks
  4. Completing tasks
  5. Putting it together

16 Advanced string operations

  1. split and join
  2. replace
  3. trim and pad
  4. RegExp
  5. StringBuffer
  6. Summary - Advanced strings

17 Enums

  1. Defining enums
  2. Enum values
  3. Enhanced enums
  4. switch with enum
  5. Enum and patterns
  6. Summary - Enums

18 Exceptions

  1. try/catch
  2. throw
  3. finally
  4. The Exception class
  5. on clause
  6. Summary - Exceptions

19 Async basics

  1. Future
  2. async/await
  3. then
  4. Future.error
  5. Future.wait
  6. Summary - Async basics

20 Beginner final

  1. Project design
  2. Classes
  3. Collections
  4. Error handling
  5. Putting it together