dmakwt / unicode_dart_course

Dart #1

• main method

void main() {
  
}

• print function

void main() {
  print('أهلا وسهلا');
}

---

• variables (start with lowercase, Camel case, can't start with @ ! etc, you can start with $)

void main() {
   String name = 'Dhari';
   String name2 = "Dhari";
   int age = 24;
   double height = 174.5;
   bool likesPizza = true;
    
   print(name);
   print(age);
}

• var keyword

void main() {
   var name = 'Dhari';
   var age = 23;
   var height = 174.5;
   var likesPizza = true;
    
   print(name);
   print(age);
}

• dynamic

void main() {
  dynamic name2 = 'Dhari';
  print(name2);

  name2 = 20;
  print(name2);
}

• var vs const

void main() {
  var age = 22;
  print(age);
  
  age = 25;
  print(age);

  const age1 = 22;
  print(age1);
  
  final age2 = 22;
  print(age2);
}

• null safety

void main() {
  String value1 = 'abc'; // String
  //  String value1 = null; -> error
  
  String? value2 = null; // null or String

  print(value1);
  print(value2);
}

---

• طباعة المتغير داخل نص

void main() {
   var firstName = 'Dhari';
   var age = 23;
  
   print('Name: ' + firstName +' age: ' + age.toString());
   print('Name: $firstName age: $age');
}

• Convert String to double or int

void main() {
  String height3 = '170';
  double height4 = 4;
  
  // print(height3 + height4);  -> error
  
  print(double.parse(height3) + height4);
}

• Convert int or double to String

void main() {
  int age = 50;
  String myAge = age.toString();
  print(myAge);
  
  // or
  int age = 50;
  String myAge = '$age';
  print(myAge);
  
}

- Comments
```dart
void main() {
  // Hi
  
  /*
    test
    test
  */
}

---

• String methods - toUpperCase(), toLowerCase()

void main() {
   String title = 'Flutter course';
   print(title.toUpperCase());
   
  title = title.toLowerCase();
  print(title);
}

• String methods - replaceAll()

void main() {
  String myFood = 'I love pasta';
  print(myFood);
  String myFood2 = myFood.replaceAll('pasta', 'pizza');
  print(myFood2);
}

---

• Arithmatics ( + - * / )

void main() {
  int x = 10;
  int x2 = 20;
  print(x + x2);

  int x3 = x + 11;
  print(x3);
}

• Operators (== , != , >= , > , <= , <)

void main(){
  print(10 == 5);
  print(10 != 5);
  print(10 >= 5);
  print(10 > 5);
  print(10 <= 5);
  print(10 < 5);
}

• Operators (|| , &&)

void main(){
  print(10 < 5 || 5 < 7);
  print(10 < 5 && 5 < 7);
}

• Operators (!)

void main(){
  print(!(10 > 5));
}

---

Part2 - Conditions

• if condition

void main() {
  var grade = 80;

  if (grade >= 90) {
    print('A');
  } else if (grade >= 80) {
    print('B');
  } else if (grade >= 70) {
    print('C');
  } else if (grade >= 60) {
    print('D');
  } else {
    print('F');
  }
}

---

List (Array) - المصفوفة عبارة عن متغير واحد مكون من عدة قيم من نفس النوع

• Create List - the index start from zero

void main() {
  // List studentList = ['Dhari', 'Ahmed'];
  var studentList = ['Dhari', 'Ahmed'];

  print(studentList[0]);
  print(studentList[1]);

  // change the list value
  studentList[0] = 'Mohammed';
  print(studentList[0]);
}

• List method - add(value)

void main() {
  var studentList = ['Dhari', 'Ahmed'];
  print(studentList);

  studentList.add('Khaled');
  print(studentList);
}

• List method - insert(index, value)

void main() {
  var studentList = ['Dhari', 'Ahmed'];
  print(studentList);

  studentList.insert(1, 'Nasser');
  print(studentList);
}

• List method - removeAt(index)

void main() {
  var studentList = ['Dhari', 'Ahmed'];
  print(studentList);
  studentList.removeAt(1);
  print(studentList);
}

---

Loops

• For loop

void main() {
  for (var i = 1; i <= 5; i++) {
    print("Line $i");
  }
}

• print List values

void main() {
  var studentList = ['Dhari', 'Ahmed', 'Mohammed'];

  for (var i = 0; i < studentList.length; i++) {
    print(studentList[i]);
  }
}

void main() {
  var studentList = ['Dhari', 'Ahmed', 'Mohammed'];

  for (var student in studentList) {
    print(student);
  }
}

---

Function - الدالة عبارة عن مجموعة أوامر مجمعينها بمكان واحد وتنفذ هالاوامر لمن نستدعي الدالة

• create function

void sayHi() {
  print('Hi');
  print('Welcome');
}

void main() {
  sayHi();
  sayHi();
  sayHi();
}

• pass values inside function

void main() {
  // Before
  const name = 'Dhari';
  const age = 23;
  print('My name: $name, and my age: $age');

  const name2 = 'Rashid';
  const age2 = 26;
  print('My name: $name2, and my age: $age2');

  // After
  printBio('Dhari', 23);
  printBio('Rashid', 26);
}

void printBio(String name, int age) {
  print('My name: $name, and my age: $age');
}

• return value from function

void main() {
  String bio = printBio('Dhari', 23);
  print(bio);
}

String printBio(String name, int age) {
  return 'My name: $name, and my age: $age';
}

• positional argument vs named argument

void main() {
  // before
//   final bio = printBio('Dhari', 23);
//   print(bio);

  // After
//   final bio = printBio(name: 'Dhari', age:23);
  final bio = printBio(age: 23, name: 'Dhari');
  print(bio);
}

String printBio({required String name, required int age}) {
  return 'My name: $name, and my age: $age';
}

• default value (Optional)

void main() {
  final bio1 = printBio(name: 'Dhari', age: 23);
  print(bio1);

  final bio2 = printBio(name: 'Dhari');
  print(bio2);

}

String printBio({required String name, int age = 30}) {
  return 'My name: $name, and my age: $age';
}

---

• Create Map

void main() {

 var person = {
    'name': 'Dhari',
    'age': 24,
    'height': 174,
  };
  
  // Keys not index
  print(person['name']);
  print(person['age']);
  
  // Change Map values
  person['age'] = 40;
  print(person);
}