Notes

import 'package:flutter/material.dart';

void main() {
runApp(MyApp());
}

class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
title: 'Kindacode.com',
home: HomePage(),
);
}
}

class HomePage extends StatefulWidget {
@override
_HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
// the controller for the text field associated with "height"
final _heightController = TextEditingController();

// the controller for the text field associated with "weight"
final _weightController = TextEditingController();

// The BMI
double? _bmi;

// the message at the beginning
String _message = 'Биеийн жин болон өндөрөө оруулна уу!!';

void _calculate() {
final double? height = double.tryParse(_heightController.value.text);
final double? weight = double.tryParse(_weightController.value.text);

// Check if the inputs are valid
if (height == null || height <= 0 || weight == null || weight <= 0) {
setState(() {
_message = "Your height and weigh must be positive numbers";
});
return;
}

setState(() {
_bmi = weight / (height * height);
if (_bmi! < 18.5) {
_message = "Туранхай";
} else if (_bmi! < 25) {
_message = 'Хэвийн жин';
} else if (_bmi! < 30) {
_message = 'Таргалалттай';
} else {
_message = 'Хэт таргалалттай';
}
});
}

@override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Color.fromARGB(255, 154, 189, 221),
body: Center(
child: Container(
width: 320,
child: Card(
color: Colors.white,
elevation: 10,
child: Padding(
padding: const EdgeInsets.all(20),
child: Column(
mainAxisSize: MainAxisSize.min,
children: [
TextField(
keyboardType:
TextInputType.numberWithOptions(decimal: true),
decoration: InputDecoration(
border: OutlineInputBorder(),
hintText: 'жишээ:180',
labelText: 'Өндөр (m)'),
controller: _heightController,
),
TextField(
keyboardType:
TextInputType.numberWithOptions(decimal: true),
decoration: InputDecoration(
border: OutlineInputBorder(),
hintText: 'жишээ: 60',
labelText: 'Жин (kg)',
),
controller: _weightController,
),
ElevatedButton(
onPressed: _calculate,
child: Text('Тооцоолох'),
),
SizedBox(
height: 30,
),
Container(
child: Text(
_bmi == null
? 'Утга оруулаагүй'
: _bmi!.toStringAsFixed(2),
style: TextStyle(fontSize: 25),
textAlign: TextAlign.center,
),
),
SizedBox(
height: 20,
),
Container(
child: Text(
_message,
textAlign: TextAlign.center,
),
)
],
),
),
),
),
));
}
}