Basics of dart language

break and continue keyword.dart

//BREAK stmt
// break keyword
// using label here we can  use outerloop for break stmt 
void main(){
  
  myouterloop: for(int i=1; i<=3; i++){
   innerloop: for(int j=1; j<=3; j++){
      print("$i $j");
      if(i == 2 && j == 2)
      break myouterloop; 
    }
  }
   	
}
// CONTINUE KEYWORD

// CONTINUE keyword
// using label
void main(){
  
 outer: for(int i=1; i<=3; i++){
   innerloop: 	for(int j=1; j<=3; j++){
   				
        if(i == 2 && j == 2){
        continue innerloop;
      }
     print("$i $j");
  } 
 }
}  

condition expression.dart

void main(){
  // condition expression
  
  // 1. condition ? exp1 : exp2
  //if condition is true then exp1 execute otherwise evaluate and return the value of exp2.
  var a =2;
  var b= 3;
  int smallnumber;
  
/*  if(a>b)
    print("$a is greater");
    else
    print("$b is greater");
  
  a>b ? print("$a is greater") : print("$b is greater"); 
  smallnumber = condition ? exp1 : exp2 */
  
  smallnumber = a<b ? a : b;
  print("$smallnumber  is smaller");
  
  // exp1 ?? exp2
  // if expression is non-null, return it's value; otherwise evaluate and return value of exp2.
  
  String name = "peter";
  String toprint = name ?? "guest user";
  print(toprint);
}

data type and variable declare.dart

void main(){
    int age=10;
    String name="vraj";
    double percentage=67.666;
    double hexvalue= 0xEEAABBCCDD;
    double expo = 1.22e45;
    bool isvalid = true;
    
    print(age);
    print(name);
    print(percentage);
    print(hevalue);
    print(expo);
    print(isvalid);
}

define final and const keyword.dart

/* Constants: final and const keyword
-> If you never want to change  a value then use final and const keyword.
-> final name="peter";
const PI = 3.14;
-> difference between final and const
-> final variable can only be set once and it is initialized when accessed.
->  const variable is implicitly final but it is a compile time constant
    -> i.e. it is initialized during compilation time
 -> instance variable can be final but cannot be const.
 -> if a constant at class level then make it static const

void main(){
  
  	// final keyword
  
  final cityname = 'vadodara';
  final String nickname = 'Bobby';
  // cityname = 'vadodara'; we cannot assign again cityname
   final String countryname = 'India';
 	
  print(cityname);
  print(nickname);
  print(countryname);
  
  // const keyword
  
  const PI = 3.14;	// const double PI = 3.14;
  print(PI); 
  
  const double gravity = 9.8;
  print(gravity);
	}
class circle{
  	
  final color = 'red';
  static const PI = 3.14;		// here in class you have to write static in front of const
  
}

if else.dart

void main(){
  
  // IF AND ELSE STATEMENTS
  var salary = 50000;
  
  if(salary > 5000 )
    
    print("true");
  
  else
    print("false");
  
  // if else if ladder statment 
  var marks = 1000;
  
  if (marks >= 80 && marks <100){
    print("grade A+");
  }
  else if(marks >= 60 && marks < 79)
  {
    print("grade B"); }
  else if(marks<=40)
  {
    print("fail");
  }else
  {
    print("invalid marks");
  }
}

loop control stmt.dart

/* Iterator:  
  
          Loop: definite-> for loop
               Indefinite -> while loop and do while loop */
// FOR LOOP
 void main(){
   
   for(int i=0; i<=10; i++)
   {
     if(i % 2 == 0){
     print(i);
     }
   }
   
   // for...in loop
   List planetlist = ["mercury","venus","earth","mars"];
   
   for(String planet in planetlist)
     print(planet);
 }

// WHILE LOOP
/* WHILE LOOP SYNTAX 
initializer counter
while (condition){
put executes code
increment and  decrment
} */
void main(){
  
	int i = 0;
  while ( i<=10){
    if(i % 2 == 0){
      print(i); }
    i++;
  }
}

// DO-WHILE LOOP
void main(){
  var i = 0;
  do{
    if(i % 2 == 0){
    print(i); }
    i++;
  }while(i<=20);
}

String, literal and string interpolation.dart

void main(){
// literal
  
 var isvalid = true;
  var x = 2;
    var value = 45.55;
   "hello";
  
  //various way to define string literal in dart
  String s1 = 'single';
  String s2 = "double";
  String s3 = 'It\'s easy';		// here we have use escap character  so we use backslash now it read 																				full stmt
  String s4 = "It's easy";   // here we have use double slash and it read full stmt
  
  // large statment (we don't have to use + sign to add two stmt)
  String s5 = 'this is going to be a very long string.' 
    													'this is just a sample string demo in  dart programming language.';   
  
  // string interpolation : use ["my name is $name"] instead of ["my name is + name"]
  
  String name = "vraj";
   
  /* In dart language using + sign is very bad impression so here string interpolation come into picture
String message = "my name is " + name;  */
   // String message = "my name is $name";
   
  print("my name is $name"); 
 // print("the number is character in String vraj is " + name.length.toString() );
  print("the number is character in String vraj is ${name.length}");
  
  int l = 20;
  int b = 10;
  print("the sum of l and b is  ${l+b}");
   print("the sum of $l and $b is  ${l+b}");
  print("the area of the rectangle is ${l*b}");
}

switch case.dart

void main(){
  
  // switch case stmt is applicable for only  'int' and 'String'. here bool and double value is not allowed
  
  var grade = 'A';
  
  switch(grade)
  {
    case 'A': 
      	print("excellent grade");
      	break;
    case 'B': 
      	print("good work");
      	break;
    case 'C':
      		print("good work but work hard");
      		break;
    case 'D':
      		print("you have failed");
      		break;
      default : print("exit");
  }
}