dartLearning

Timer.dart

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+import 'dart:async';
+
+void main() {
+  int FromTime = 11;
+  Timer.periodic(Duration(seconds: 1), (timer) {
+    if (FromTime == 1) {
+      timer.cancel();
+    } else {
+      FromTime--;
+      print(FromTime);
+    }
+  });
+}

calculator.dart

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+import 'dart:io';
+
+void main() {
+  try {
+    stdout.write("Enter First number: ");
+    int firstNum = int.parse(stdin.readLineSync().toString());
+    stdout.write("Enter Second number: ");
+    int secondNum = int.parse(stdin.readLineSync().toString());
+    var cal = Calculator();
+    //Sum = return type
+    var sum = cal.sum(a: firstNum, b: secondNum);
+    print("Sum: " + sum.toString());
+    //Other operation = non return type
+    cal.sub(a: firstNum, b: secondNum);
+    cal.mult(a: firstNum, b: secondNum);
+    cal.div(a: firstNum, b: secondNum);
+  } on FormatException catch (number) {
+    print("Invlaid number format in input field");
+  } catch (error) {
+    print(error);
+  }
+}
+
+class Calculator {
+  late int num1;
+  late int num2;
+
+  int sum({a, b}) {
+    this.num1 = a;
+    this.num2 = b;
+    return num1 + num2;
+  }
+
+  void sub({a, b}) {
+    this.num1 = a;
+    this.num2 = b;
+    print("Substraction: ${num1 - num2}");
+  }
+
+  void mult({a, b}) {
+    this.num1 = a;
+    this.num2 = b;
+    print("Multiplication: ${num1 * num2}");
+  }
+
+  void div({a, b}) {
+    this.num1 = a;
+    this.num2 = b;
+    print("Division: ${num1 / num2}");
+  }
+}

dice.dart

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+import 'dart:math';
+
+void main() {
+//   DateTime todaydt = DateTime.now();
+//   var milisec = todaydt.millisecond;
+
+//   var randomFace = Dice();
+//   print("You get: ");
+//   print('${randomFace.diceFace(a: milisec)}');
+// }
+
+// class Dice {
+//   late int a;
+//   int diceFace({a}) {
+//     return (a % 6 + 1);
+//   }
+var list = [1,2,3];
+var ran = Random();
+print(list[ran.nextInt(list.length)]);
+
+}
+

tips_tricks.dart

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+void main() {
+  /*String repeat =
+      "lal kumar pun" * 5; //used on testing purpose for many dummy datas
+  print(repeat); */ // This is string multiplications
+  // store();
+  SpreadOperator();
+}
+//--------------------Use of future keywords with async and await keywords-----------------------------------
+
+/* void store() async {
+  //async and await used during using of future only
+  var data = await downloads();
+  print(data);
+}
+
+Future<String> downloads() {
+  var result = Future.delayed(Duration(seconds: 3), () {
+    return "hello future code works dear lal for async and await";
+  });
+  return result; 
+} */
+
+/* -----------------------Use of future keywords with then keywords-----------------------------------
+
+// using then keyword have feautures of error in dart languages than that of await and async
+void store() {
+  // Future<String> data = downloads(); neeeds in future
+  var data = downloads(); // needs immediatley
+  data.then((response) => print(response), onError: (Error) {
+    print(Error);
+  });
+}
+
+Future<String> downloads() {
+  Future<String> result = Future.delayed(Duration(seconds: 3), () {
+    return Future.error("hello error for then keywords");
+  });
+  return result;
+}*/
+
+//-------------------SPREAD OPERATOR-------------------------------------------------------------------
+
+void SpreadOperator() {
+  var marks = 30;
+  //-----------------IF ELSE shortcut
+  // bool ifElseShorcut = true;
+  // ifElseShorcut ? "its true condition" : "else false condition";
+  List<String> std = [
+    "lal",
+    if (marks > 40) ...["not match"],
+    if (marks > 20) ...["match"]
+  ];
+  print(std);
+}