1. Data types

2. Variables

3. Operators 

4. user input

Explanation:-

1. Data Types

Data types specify what kind of data a variable can hold. Dart is statically typed, so each variable has a specific data type, either explicitly declared or inferred.

Common Data Types in Dart:

• int: Holds integer values.

• double: Holds decimal numbers (floating-point).

• String: Holds a sequence of characters.

• bool: Holds either true or false.

• List: An ordered collection of items.

• Map: A collection of key-value pairs.

2. Variables

Variables are containers that store data values. In Dart, you declare variables using var, final, or const.

• var: Type is inferred based on the assigned value and can be reassigned.

• final: Value can only be set once and cannot be changed.

• const: Similar to final but is a compile-time constant.

3. Operators

Dart provides several types of operators, such as arithmetic, relational, logical, and assignment operators.

Examples of Operators:

• Arithmetic Operators: +, -, *, /, %

• Relational Operators: ==, !=, >, <, >=, <=

• Logical Operators: && (and), || (or), ! (not)

• Assignment Operators: =, +=, -=, etc.

4. User Input

Dart has no native way to take user input directly. However, if you’re using Dart in a console environment (like Dart CLI), you can use the dart:io library to take input.

In this example:

• stdin.readLineSync() is used to take input as a string.

• int.parse() converts a string input to an integer.

Data Types:

Example:

void main() {

 int age = 25;   //integer types

 double price = 99.99; //Double types

 String name = "John";  //String types

 bool isLoggedIn = true;  //Boolean types types

 List<int> numbers = [1, 2, 3, 4];  //List  types

 Map<String, String> user = {'name': 'Alice', 'country': 'USA'};  //Map types types

 print("Age: $age");

 print("Price: $price");

 print("Name: $name");

 print("Is Logged In: $isLoggedIn");

 print("Numbers: $numbers");

 print("User Info: $user");

}

Variables-

Example:

void main() {

 var name = "Emma"; // inferred as String

 final int age = 30; // explicitly declared as int

 const double pi = 3.14;

 print("Name: $name");

 print("Age: $age");

 print("PI: $pi");

}

Operators:-

Example:

void main() {

 int a = 10;

 int b = 5;

 // Arithmetic operations

 print("Addition: ${a + b}");

 print("Subtraction: ${a - b}");

 print("Multiplication: ${a * b}");

 print("Division: ${a / b}");

 print("Modulo: ${a % b}");

 // Relational operations

 print("Is a greater than b? ${a > b}");

 print("Is a equal to b? ${a == b}");

 // Logical operations

 bool isSunny = true;

 bool isWeekend = false;

 print("Is it sunny and weekend? ${isSunny && isWeekend}");

 print("Is it sunny or weekend? ${isSunny || isWeekend}");

}

Input and Output:

Example:

import 'dart:io';

void main() {

 print("Enter your name:");

 String? name = stdin.readLineSync();

 print("Enter your age:");

 int age = int.parse(stdin.readLineSync()!);

 print("Hello, $name! You are $age years old.");

}

Explanation:

1. Integer Input: Using int.parse(stdin.readLineSync()!) to read and parse an integer.

2. Double Input: Using double.parse(stdin.readLineSync()!) to read and parse a double.

3. String Input: Simply using stdin.readLineSync()! to read a string.

4. Boolean Input: Taking input as a string (e.g., yes/no) and converting it to a Boolean value.

5. List Input: Reading a comma-separated string, splitting it, and converting each item to an integer with map(int.parse).

//we can take user input using the dart:io library.

import 'dart:io';

void main() {

 // Taking an integer input

 print("Enter your age:");

 int age = int.parse(stdin.readLineSync()!);

 print("You entered age: $age");

 // Taking a double input

 print("Enter your height in meters:");

 double height = double.parse(stdin.readLineSync()!);

 print("You entered height: $height meters");

 // Taking a string input

 print("Enter your name:");

 String name = stdin.readLineSync()!;

 print("Hello, $name!");

 // Taking a boolean input

 print("Are you a student? (yes/no):");

 String isStudentInput = stdin.readLineSync()!.toLowerCase();

 bool isStudent = isStudentInput == 'yes';

 print("Student status: $isStudent");

 // Taking a list of numbers (comma-separated)

 print("Enter a list of numbers separated by commas:");

 String numbersInput = stdin.readLineSync()!;

 List<int> numbers = numbersInput.split(',').map(int.parse).toList();

 print("You entered the numbers: $numbers");

 // Calculating and outputting some derived values

 int nextAge = age + 1;

 double heightInCm = height * 100;

 print("Next year, you will be $nextAge years old.");

 print("Your height in centimeters is $heightInCm cm.");

}

OutPuts:

Enter your age:

25

You entered age: 25

Enter your height in meters:

1.75

You entered height: 1.75 meters

Enter your name:

Alice

Hello, Alice!

Are you a student? (yes/no):

yes

Student status: true

Enter a list of numbers separated by commas:

1,2,3,4,5

You entered the numbers: [1, 2, 3, 4, 5]

Next year, you will be 26 years old.

Your height in centimeters is 175.0 cm.