Dart Variables

variables.dart

void main() {
  // Way 1
  print('----Declare Way 1----'); 
  var unlimited;
  unlimited = 'unlimited';
  print(unlimited);
  // 'unlimited' => 1000.00, ALLOWED
  unlimited = 1000.0;
  print(unlimited);
  
  
  // Way 2 - Recommended
  print('----Declare Way 2----'); 
  String name = 'nikk1';
  int age = 20;
  double salary = 1000.00;
  bool married = true;

  
  print(name);
  print(age);
  print(salary);
  print(married);
  
  // 'nikk1' => 1000.00, NOT ALLOWED
  // name = 1000.00; 
  
  
  // ---------- Properties ---------- //
  String properties = '\t I bought a new iPhone \n';
  print('------properties-------');
  print(properties.length); // 25
  print(properties.trim().length); // 21
  
  properties = '';
  print(properties.isEmpty); // true
  properties = '  \t\n';
  print(properties.isEmpty); // false
  print(properties.trim().isEmpty); // true
  properties = null;
  // print(properties.isEmpty); => Error
  
  String unintialized;
  print(unintialized); // null
  // print(unintialized.isEmpty); => Error
  // print(unintialized.isNotEmpty); => Error
  
  // substring 
  // @String
  print('----1. substring----'); 
  print(name.substring(0)); // nikk1
  print(name.substring(1, 3)); // ik
    
  // startsWith
  // @String
  print('----2. startWith----'); 
  print(name.startsWith('i')); // false
  print(name.startsWith('i', 1)); // true
  print(name.startsWith(new RegExp(r'\w'))); // true
  print(name.startsWith(new RegExp(r'\d'))); // false
  print(name.startsWith(new RegExp(r'\d'), 4)); // true
  print(name.startsWith(new RegExp(r'[A-Za-z]'))); // true
  print(name.startsWith(new RegExp(r'[A-Za-z]{1}'), 4)); // false
  print(name.startsWith(new RegExp(r'[A-Za-z]{5}'))); // false
  
  // split 
  // @List
  String sentences = 'John took 20 min to resolve this; John just left office';
  print('----3. split----'); 
  print(sentences.split(';')); // ['John took 20 min to resolve this',  'John just left office']
  
  // replaceAll
  // @String
  print('----4. replaceAll----'); 
  String unpurified = 'Johnny really loves drugs and guns';
  print(unpurified.replaceAll(new RegExp(r'(drugs|guns)'), '***')); // Johnny really loves *** and ***
  
  // toLowerCase
  // @String
  print('----5. toLowerCase----'); 
  String playername = 'Kevin Snake';
  print(playername.toLowerCase());// kevin snake
  print(playername.toUpperCase()); // KEVIN SNAKE
  
  // Value Checking
  // playername = null
  print('----6. Value Checking----'); 
  playername = null;
  print(playername);
  if (playername == null) { print('yes');} // yes, playername == null
  // print(playername.toLowerCase()); => Exception
}