Dart

/*Literals

true, 'string', 10, 5.5.

*/

// String concats automatically in dart means you don't have to write + (Eg: 'yasho' 'Vardhan' = 'yashoVardhan' )

// To access variable in a string use $var in string

// toString() method

// var.length method

// str.replaceAll(strToReplace, str)

// string.subString(start index, end index[optional]) = slicing

// $ symbol takes only one word and not any method, so use ${var.length}

// Convert String to int or double -> double.parse(str)/int.parse(str)

void main() {  // Runs when code is executed

  // int number = 15;

  // String greet = greeting();

  // String name = 'yash';

  // bool isNight = true;

  // dynamic yash = 'YASHO';  // To change type of variable

  // int age = getAge();

  // num Number;  // This can take value of int and double

  // yash = 30;

  // List names = ['yash', 'singh', 'rajput'];

  // List<String> names = ['yash', 'singh', 'rajput'];

  // names.add('lugia');  // append

  // names.remove('rajput');

  // double angle = 45.78;  // float

  // double number = 1.45e5  Use e for 10 ki power 

  // var variable = 10;  // var Can take value of any DataType.

  // By default the value of any variable is null

  User username = User('yash', 18);

  print(username.name);

}

// void means it will not return anything

String greeting(){ // DataTpye the function will return

  return 'hello';

}

/* FUNCTIONS */

// By default a function always return null

// To pass a function as a parameter to a function use dynamic datatype 

// Arrow function (fat arrow)

int getAge() => 18;

var getSquare = (a) => a*a; 

int area(int l, int b) => l*b;

var cube = (num a) => a*a*a;

int yash(num a) => a*a*a;

int area(int length, int breadth){ // length and breadth are required parameters

  return length * breadth;

}

// Optional parameters = names(String n1, [String n2, String n3])

// Named parameters = names(String n1, {String n2})

// Optional default parameters = names(String n1, int num = 10)

class User {

  // Variables

  // String name = 'yash';

  // int age = 18;

  // methods

  void login(){

    print('Logged in');

  }

  // constructor

  String name;

  int age;

  User(String name, int age){

    this.name = name;

    this.age = age;

  }

}

// Inheritance

class Superuser extends User{

  void publish(){

    print('Published');

  }

  Superuser(String name, int age): super(name, age);

}

MATH module

import 'dart:math' as m;

   FUNCTIONS

acos(num x) → double

Converts x to a double and returns its arc cosine in radians. [...]

asin(num x) → double

Converts x to a double and returns its arc sine in radians. [...]

atan(num x) → double

Converts x to a double and returns its arc tangent in radians. [...]

atan2(num a, num b) → double

A variant of atan. [...]

cos(num radians) → double

Converts radians to a double and returns the cosine of the value. [...]

exp(num x) → double

Converts x to a double and returns the natural exponent, e, to the power x. [...]

log(num x) → double

Converts x to a double and returns the natural logarithm of the value. [...]

max<T extends num>(T a, T b) → T

Returns the larger of two numbers. [...]

min<T extends num>(T a, T b) → T

Returns the lesser of two numbers. [...]

pow(num x, num exponent) → num

Returns x to the power of exponent. [...]

sin(num radians) → double

Converts radians to a double and returns the sine of the value. [...]

sqrt(num x) → double

Converts x to a double and returns the positive square root of the value. [...]

tan(num radians) → double

Converts radians to a double and returns the tangent of the value. [...]

  CONSTANTS

e → const double

Base of the natural logarithms. [...]

2.718281828459045

ln2 → const double

Natural logarithm of 2. [...]

0.6931471805599453

ln10 → const double

Natural logarithm of 10. [...]

2.302585092994046

log2e → const double

Base-2 logarithm of e.

1.4426950408889634

log10e → const double

Base-10 logarithm of e.

0.4342944819032518

pi → const double

The PI constant.

3.1415926535897932

sqrt1_2 → const double

Square root of 1/2.

0.7071067811865476

sqrt2 → const double

Square root of 2.

1.4142135623730951

EXCEPTIONS:

try {

  Money(-5);

}

on IntegerDivisionByZeroException{

 print('zero'); 

}

catch(e){

  e.error();

}

finally{

  print('arceus');

}

}

// Custom Exception

class Hello implements Exception{

  void error(){

    print('Yashovardhan Singh Rajput');

  }

}

void Money(int num){

  if (num <= 0){

    throw new Hello();

  }