Dart-1
Dart Basics
Welcome to Day-1 of learning Dart basics! In this session, we will cover the fundamental concepts of Dart programming language. By the end of this session, you will have a solid understanding of variables, types, functions, operators, conditional statements, loops, and collections such as lists and maps. Additionally, we will introduce some functional programming concepts like map, filter, and reduce.
Variables
Variables are used to store data values that can be used later in the program. In Dart, you can declare variables using the var, final, or const keyword.
var name = 'John'; // type inferred
final age = 30; // can't be reassigned
const PI = 3.14; // compile-time constant
Types
Dart is a statically typed language, which means that each variable must have a specific type. Dart supports several built-in types, including int, double, String, bool, and more.
int number = 10;
double decimal = 3.14;
String message = 'Hello World';
bool isTrue = true;
Functions
Functions are a set of instructions that can be reused throughout the program. Dart supports two types of functions: named functions and anonymous functions (also known as lambda functions).
// Named Function
int sum(int a, int b) {
return a + b;
}
// Anonymous Function
var product = (int a, int b) => a * b;
Operators
Operators are symbols that perform operations on operands. Dart supports several types of operators, including arithmetic, comparison, logical, and bitwise operators.
int a = 10, b = 20;
print(a + b); // 30
print(a < b); // true
print(!(a < b)); // false
print(a & b); // 0
If-Else
Conditional statements are used to execute different blocks of code depending on whether a condition is true or false. Dart supports if-else statements and ternary operators.
int age = 20;
if (age < 18) {
print('You are not eligible to vote');
} else {
print('You can vote');
}
// Ternary operator
age < 18 ? print('You are not eligible to vote') : print('You can vote');
Loops
Loops are used to execute a block of code repeatedly. Dart supports for loops, while loops, and do-while loops.
// for loop
for (var i = 1; i <= 10; i++) {
print(i);
}
// while loop
int i = 1;
while (i <= 10) {
print(i);
i++;
}
// do-while loop
int j = 1;
do {
print(j);
j++;
} while (j <= 10);
Lists
A list is a collection of elements in a specific order, where each element can be of any data type. In Dart, lists are represented using square brackets ([]) and can be created in several ways, such as:
List<String> names = ['John', 'Mary', 'Bob'];
List<int> numbers = [1, 2, 3, 4];
List<dynamic> mixed = [1, 'two', true];
Accessing Elements
You can access an element in a list by its index. In Dart, the index of the first element in a list is 0, and the index of the last element is length - 1. You can access an element using the square bracket notation ([]):
List<String> fruits = ['apple', 'banana', 'orange'];
print(fruits[0]); // apple
Adding Elements
You can add an element to the end of a list using the add method:
List<String> fruits = ['apple', 'banana', 'orange'];
fruits.add('grape');
print(fruits); // [apple, banana, orange, grape]
You can also add elements to a specific position in the list using the insert method:
List<String> fruits = ['apple', 'banana', 'orange'];
fruits.insert(1, 'grape');
print(fruits); // [apple, grape, banana, orange]
Removing Elements
You can remove an element from a list using the remove method:
List<String> fruits = ['apple', 'banana', 'orange'];
fruits.remove('banana');
print(fruits); // [apple, orange]
You can also remove an element at a specific position in the list using the removeAt method:
List<String> fruits = ['apple', 'banana', 'orange'];
fruits.removeAt(1);
print(fruits); // [apple, orange]
Updating Elements
You can update an element in a list by assigning a new value to it:
List<String> fruits = ['apple', 'banana', 'orange'];
fruits[1] = 'grape';
print(fruits); // [apple, grape, orange]
Important Functions
Dart provides several useful functions for working with lists. Here are some of the most commonly used functions:
mapThemapfunction applies a transformation function to each element of a list and returns a new list with the transformed elements. The transformation function takes an element of the list as input and returns a new value. Here's an example:List<int> numbers = [1, 2, 3, 4, 5];
List<int> doubledNumbers = numbers.map((number) => number * 2).toList();
print(doubledNumbers); // [2, 4, 6, 8, 10]whereThewherefunction returns a new list that contains only the elements that satisfy a certain condition. The condition is specified by a boolean function that takes an element of the list as input and returns a boolean value. Here's an example:List<int> numbers = [1, 2, 3, 4, 5];
List<int> evenNumbers = numbers.where((number) => number % 2 == 0).toList();
print(evenNumbers); // [2, 4]reduceThereducefunction applies a binary function to the elements of a list in a cumulative way and returns a single value.List<int> numbers = [1, 2, 3, 4, 5];
int sum = numbers.reduce((a, b) => a + b);
print(sum); // 15