Mad With Flutter lab

import 'package:flutter/material.dart';

void main() => runApp(const MaterialApp(home: CalculatorApp()));

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

  @override
  State createState() => _CalculatorAppState();
}

class _CalculatorAppState extends State {
  final num1 = TextEditingController();
  final num2 = TextEditingController();
  String result = '';

  void calculate(String op) {
    double a = double.tryParse(num1.text) ?? 0;
    double b = double.tryParse(num2.text) ?? 0;
    double res = 0;

    switch (op) {
      case '+': res = a + b; break;
      case '-': res = a - b; break;
      case '*': res = a * b; break;
      case '/': res = b != 0 ? a / b : 0; break;
    }

    setState(() => result = 'Result: $res');
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Simple Calculator')),
      body: Padding(
        padding: const EdgeInsets.all(20),
        child: Column(
          children: [
            TextField(controller: num1, keyboardType: TextInputType.number, decoration: const InputDecoration(labelText: 'Number 1')),
            TextField(controller: num2, keyboardType: TextInputType.number, decoration: const InputDecoration(labelText: 'Number 2')),
            const SizedBox(height: 20),
            Row(
              mainAxisAlignment: MainAxisAlignment.spaceAround,
              children: ['+', '-', '*', '/'].map((op) {
                return ElevatedButton(
                  onPressed: () => calculate(op),
                  child: Text(op),
                );
              }).toList(),
            ),
            const SizedBox(height: 20),
            Text(result, style: const TextStyle(fontSize: 24)),
          ],
        ),
      ),
    );
  }
}