Flutter Development (Day: 1).

• In this post we are going to talk about Dart programming.
• Dart is an open-source general-purpose programming language.
• Dart is an object-oriented language with C-style syntax which can optionally trans compile into JavaScript. It supports a varied range of programming aids like interfaces, classes, collections, generics, and optional typing.
• Dart is the programming language which is used to access all the methods in Flutter SDK.
• In this post I am going to explain the basics of Dart. You don't need to master in Dart the basics is enough to get started.
• You can practice the dart here.
• Dart is similar to Java script and Java. The program starts with main() function.

void main(){
print("Hello Dart")
}
<!-- Both are same -→
void main() => print("Hello Dart")

• (=>) Arrow Funtion lets us make things easier.When your returning a single method or statement you don't need to wrap it with in curly braces and you can avoid using return statement as above.
• Arrow functions are a concise mechanism to represent functions. These functions are also called as Lambda functions.

Dart consists of

• Variables and Operators
• Classes
• Functions
• Expressions and Programming Constructs
• Decision Making and Looping Constructs
• Comments
• Libraries and Packages

Comments

// this is single line comment

/* This is a
   Multi-line comment
*/

DataTypes

Numbers => Integer(int),Double(double).
Strings => String.
Booleans => Boolean(bool).
Lists => List.
Maps => Map.
Dynamic => Dynamic(dynamic).

-

 is also a data type we can assign any data type to `var` by default it assigns `String`.



```dart
void main() {
   var name = "Flutter Dart";
   print(name);
}

Output:

 Flutter Dart

• The const keyword is used to represent a compile-time constant. Variables declared using the const keyword are implicitly final.

Operators

void main(){
  int a = 10;
  int b = 10;

  print("Addition of $a and $b: ${a+b}");
  print("Subtraction of $a and $b: ${a-b}");
  print("Multiplication of $a and $b: ${a*b}");
  print("Division of $a and $b: ${a/b}");

}

Output:

Addition of 10 and 10: 20
Subtraction of 10 and 10: 0
Multiplication of 10 and 10: 100
Division of 10 and 10: 1

• Here We can directly print the value of the variable by using $ for one value and for expression we use ${} known as string Interpolation

Decision Making

• if
• if else
• else if
• switch case

void main() {
   var a = 52;
   if(a > 0) {
      print("$a is positive");
   }
   else if(a < 0) {
      print("$a is negative");
   } else {
      print("$a is neither positive nor negative");
   }

   // Switch case

   var name = "Ramu";
   switch(name) {
      case "Kumar": {  print("Welcome $name"); }
      break;

      case "Indhu": {   print("Welcome $name"); }
      break;

      case "Ramu": {  print("Welcome $name"); }
      break;



      default: { print("Welcome Guest"); }
      break;
   }
}

Output:

52 is positive
Welcome Ramu.

Loops

// For Loop
 for (var i = 0;i<4;i++){
    print("Value of i is $i");
  }
  // While Loop
  var i = 0;
  while(i<4){
    print(i);
    i++;
  }
  // Do while loop
  var i1 = 0;
  do{
    print(i1);
    i1++;
  }while(i1<4);

Output:

// For Loop

Value of i is 0
Value of i is 1
Value of i is 2
Value of i is 3

// While Loop

Value of i is 0
Value of i is 1
Value of i is 2
Value of i is 3

// Do while loop

Value of i is 0
Value of i is 1
Value of i is 2
Value of i is 3

Lists and Map

• Lists in some of the programming languages it is also called Arrays both are same plays a crucial role in order to store a large amount of data in the form of Lists.

• The Map object is a simple key/value pair. Keys and values in a map may be of any type. A Map is a dynamic collection. In other words, Maps can grow and shrink at run time.
  

// List

  var list = [1,2,3,4,5,6,7,8,9];
   print(list);

//Assigning values dynamically to list

  var list1 = List(2);
  list1[0] = 'Ramu';
  list1[1] = 'Kumar';
  print(list1);

//Map

  var dict = {'Username':'Ramu','Password':'1111'};
   print(dict);
  var dict1 = {};
  dict1['1'] = 'Ramu';
  dict1['20'] = 'Kumar';
  print(dict1);

Output:

//List

[1, 2, 3, 4, 5, 6, 7, 8, 9]
[Ramu, Kumar]

//Map

{Username: tom, Password: pass@123}
{1: Ramu, 20: Kumar}

Functions

• Functions are the building blocks of readable, maintainable, and reusable code. A function is a set of statements to perform a specific task step by step. Functions organize the program into logical blocks of code.

void showMyName(String name){
    print("Welcome $name");
  }
showMyName("Ramu");

Output:

Welcome Ramu.

Factorial of a given number:

void main() => print(factorial(3));

  factorial(num){
    if(num<=0){
      return 1;
    }
    else{
      return num = factorial(num-1) * num;
    }
  }

Output:

6

OOPS (Object Oriented Programming)

• Dart is an object-oriented language. It supports object-oriented programming features like classes, interfaces, etc.
• A class in terms of OOP is a blueprint for creating objects. A class encapsulates data for the object. Dart gives built-in support for this concept called class.

void main() {
  Name n1 =  Name("Bugudi","Ramu");

}
class Name {
  Name(String firstName,String lastName) {
    print("Welcome $firstName $lastName");
  }
}

Output:

Welcome Bugudi Ramu

• Here we have declared a class with the help of class keyword and given Name as class name.
• A constructor is a special function of the class that is responsible for initializing the variables of the class.
• Then we created a constructor Name(String firstName,String lastName){} which takes two parameters firstName and lastName.Then we printed the message to console.
• In the main() method we instantiated n1 object for Name class and passed the required two parameters.

I think this knowledge is more than enough to get started with Flutter.From the next tutorial onwards we are going to dive deep to learn core Flutter Framework.See you guys!