🧑‍🏫01. Переменные часть 2

Видео урок

+	int, double, String	int: 5 + 3 = 8 double: 2.5 + 1.5 = 4.0 String: "Hi" + "!" = "Hi!"

-	int, double	5 - 2 = 3 4.5 - 1.5 = 3.0

*	int, double, String*	3 * 2 = 6 2.5 * 2 = 5.0 "ha" * 3 = "hahaha"

/	int, double	5 / 2 = 2.5 4 / 2 = 2.0

~/	int, double	5 ~/ 2 = 2 5.0 ~/ 2 = 2

%	int, double	5 % 2 = 1 5.5 % 2 = 1.5

++	int, double	int a = 5; a++; // a = 6

--	int, double	double d = 3.0; d--; // d = 2.0

+=	int, double, String	int a = 2; a += 3; // 5 String s = "Hi"; s += "!"; // "Hi!"

-=	int, double	int a = 5; a -= 2; // 3

*=	int, double	int a = 3; a *= 2; // 6

/=	int, double	double d = 4.0; d /= 2; // 2.0

~/=	int, double	int a = 5; a ~/= 2; // 2

%=	int, double	int a = 5; a %= 2; // 1

Исходный код

// Some code
import 'package:flutter/material.dart';

class Lesson02 extends StatefulWidget {
  const Lesson02({super.key});

  @override
  State<Lesson02> createState() => _Lesson02State();
}

class _Lesson02State extends State<Lesson02> {
  String title = '';
  int number = 0;
  double counter = 0;
  bool isAdult = true;

  var textVar = const Text('Hello');
  var name = 'Baias';
  var age = 45;

  dynamic textDynamic = const Text('Hello');
  dynamic nameDynamic = 'Baias';
  dynamic ageDynamic = 45;

  Widget text = const Text('Hello');
  Icon icon = const Icon(Icons.add);

  bool isLike = false;
  bool isChangeContainer = false;

  // TODO : =, -, +, *, /, !
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SafeArea(
        child: title.isEmpty ? const Center(child: Text('No data'),): Column(
          children: [
            Text(
              '${title.length}',
              style: const TextStyle(fontSize: 30),
            ),
            Text(
              '${title.isEmpty}',
              style: const TextStyle(fontSize: 30),
            ),
            Text(
              '${title.isNotEmpty}',
              style: const TextStyle(fontSize: 30),
            ),
            Text(
              '${title.runtimeType}',
              style: const TextStyle(fontSize: 30),
            ),
            Text(
              title,
              style: const TextStyle(fontSize: 30),
            ),
            Row(
              children: [
                ElevatedButton(
                    onPressed: () {
                      setState(() {
                        title = title.toUpperCase();
                      });
                    },
                    child: const Text('Upper case')),
                ElevatedButton(
                    onPressed: () {
                      setState(() {
                        title = title.toLowerCase();
                      });
                    },
                    child: const Text('Lower case')),
              ],
            ),
            const SizedBox(
              height: 20,
            ),
            Text(
              '$number',
              style: const TextStyle(fontSize: 30),
            ),
            Row(
              children: [
                ElevatedButton(
                    onPressed: () {
                      setState(() {
                        number = number.toString().length;
                      });
                    },
                    child: const Text('+')),
                ElevatedButton(
                    onPressed: () {
                      setState(() {
                        number--;
                      });
                    },
                    child: const Text('-')),
              ],
            ),
            Text(
              '${textVar.runtimeType}',
              style: const TextStyle(fontSize: 30),
            ),
            const SizedBox(
              height: 30,
            ),
            Row(
              mainAxisAlignment: MainAxisAlignment.spaceAround,
              children: [
                Text(title),
                Text('$name, $age'),
                Text('$nameDynamic')
              ],
            ),
            Row(
              mainAxisAlignment: MainAxisAlignment.spaceAround,
              children: [
                ElevatedButton(
                    onPressed: () {
                      setState(() {
                        title = 'Hello';
                      });
                    },
                    child: const Text('title')),
                ElevatedButton(
                    onPressed: () {
                      setState(() {
                        name = 'Bakjshdkj';
                        age = 67;
                      });
                    },
                    child: const Text('name')),
                ElevatedButton(
                    onPressed: () {
                      setState(() {
                        nameDynamic = true;
                      });
                    },
                    child: const Text('Dynamic'))
              ],
            ),
            const SizedBox(
              height: 30,
            ),
            IconButton(
              onPressed: () {
                setState(() {
                  isLike = !isLike;
                });
              },
              icon: isLike
                  ? const Icon(
                      Icons.favorite,
                      color: Colors.red,
                    )
                  : const Icon(Icons.favorite_border),
            ),

            Row(
              mainAxisAlignment: MainAxisAlignment.spaceAround,
              children: [
                Container(
                  height: isChangeContainer ? 100 : 150,
                  width: isChangeContainer ? 100 : 150,
                  color: isChangeContainer ? Colors.red : Colors.blue,
                ),
                TextButton(onPressed: (){
                  setState(() {
                    isChangeContainer = !isChangeContainer;
                  });
                }, child: const Text('change container'))
              ],
            )
          ],
        ),
      ),
    );
  }
}