1. typedef nima?

typedef — bu funksiya turlarini aniqlash uchun ishlatiladi. U funksiyaning imzosini (parametrlari va qaytaradigan qiymatini) belgilash imkonini beradi. Bu orqali kodni qayta-qayta yozishdan qochasiz va bir xil turdagi funksiyalarni boshqarish osonlashadi.

2. Foydalanish sabablari:

Kodingizni tushunarliroq qilish.

Murakkab funksiya turlarini boshqarish.

Bir xil turdagi funksiyalarni boshqarishni soddalashtirish.



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3. Oddiy misol:

typedef MyFunction = int Function(int a, int b);

int add(int a, int b) => a + b;
int subtract(int a, int b) => a - b;

void main() {
  MyFunction operation;

  operation = add;
  print('Add: ${operation(5, 3)}'); // Natija: Add: 8

  operation = subtract;
  print('Subtract: ${operation(5, 3)}'); // Natija: Subtract: 2
}

Bu yerda:

typedef MyFunction = int Function(int a, int b); — bu imzo bo‘lib, u ikki int parametrni oladigan va int qiymat qaytaradigan funksiyalarni belgilaydi.

operation o‘zgaruvchisi orqali turli xil funksiyalarni chaqira olamiz.



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4. Flutter va typedef:

Flutterda ko‘pincha typedef callback funksiyalar bilan ishlatiladi. Masalan:

typedef OnPressedCallback = void Function();

class MyButton {
  final OnPressedCallback onPressed;

  MyButton({required this.onPressed});

  void press() {
    onPressed();
  }
}

void main() {
  final button = MyButton(onPressed: () {
    print('Button pressed!');
  });

  button.press(); // Natija: Button pressed!
}

Bu yerda:

OnPressedCallback turidagi funksiya MyButton sinfida qo‘llanilgan.

onPressed funksiyasi chaqirilganida, kerakli kod ishga tushadi.



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5. Generic bilan typedef:

Dart tilida typedef generic turlar bilan ham ishlaydi.

typedef Transformer<T> = T Function(T value);

String toUpperCase(String value) => value.toUpperCase();
int doubleValue(int value) => value * 2;

void main() {
  Transformer<String> stringTransformer = toUpperCase;
  Transformer<int> intTransformer = doubleValue;

  print(stringTransformer('dart')); // Natija: DART
  print(intTransformer(10));        // Natija: 20
}


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6. typedef va anonym funksiyalar:

Ko‘pincha typedef anonym funksiyalar bilan ishlatiladi:

typedef MathOperation = int Function(int x, int y);

void main() {
  final MathOperation multiply = (x, y) => x * y;
  print(multiply(4, 5)); // Natija: 20
}


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Agar sizda typedef bo‘yicha qo‘shimcha savollar bo‘lsa, bemalol so‘rang!

Dart tilida konsolga yozuvlarni rangli qilib chiqarish uchun ANSI escape codes yordamida ishlatiladigan rang kodlari ro'yxatini taqdim etaman. Bu kodlar asosan terminalda ishlaydi va ranglarni faollashtirish uchun moslashgan bo'lishi kerak.

Rang kodlari
Quyidagi ro'yxat ranglarning ANSI escape kodlarini o'z ichiga oladi:

Rang nomi  Kod
Qizil (Red)  \x1B[31m
Yashil (Green)  \x1B[32m
Sariq (Yellow)  \x1B[33m
Ko'k (Blue)  \x1B[34m
Binafsha (Purple)  \x1B[35m
Moviy (Cyan)  \x1B[36m
Oq (White)  \x1B[37m
Qora (Black)  \x1B[30m
Standart (Reset)  \x1B[0m
Masalaning yechimi
Quyida Dartda rangli matnni terminalga chiqarish uchun misol keltirilgan:

dart
Kodni nusxalash
void main() {
  // Rang kodlari
  const String reset = '\x1B[0m';      // Reset
  const String red = '\x1B[31m';       // Qizil
  const String green = '\x1B[32m';     // Yashil
  const String yellow = '\x1B[33m';    // Sariq
  const String blue = '\x1B[34m';      // Ko'k
  const String purple = '\x1B[35m';    // Binafsha
  const String cyan = '\x1B[36m';      // Moviy
  const String white = '\x1B[37m';     // Oq

  // Rangli matnlarni chiqarish
  print('${red}Bu qizil matn$reset');
  print('${green}Bu yashil matn$reset');
  print('${yellow}Bu sariq matn$reset');
  print('${blue}Bu ko\'k matn$reset');
  print('${purple}Bu binafsha matn$reset');
  print('${cyan}Bu moviy matn$reset');
  print('${white}Bu oq matn$reset');
}
Muhim eslatma
ANSI rang kodlari barcha terminallarda ishlamasligi mumkin. Masalan, ba'zi Windows terminallari qo'shimcha sozlashni talab qiladi.
Ranglarni ishlatishdan oldin terminalingizda ANSI kodlari qo'llab-quvvatlanishini tekshiring.
Agar qo'shimcha savollaringiz bo'lsa, bemalol so'rang! 😊

import 'package:flutter/material.dart';
import 'dart:io' show Platform; // Platform tekshirish uchun
import 'package:flutter/foundation.dart' show kIsWeb;

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(title: Text('MediaQuery Test')),
        body: Center(
          child: LayoutBuilder(
            builder: (context, constraints) {
              double width = MediaQuery.of(context).size.width;

              String platform = kIsWeb
                  ? 'Web'
                  : Platform.isAndroid
                      ? 'Android'
                      : 'Boshqa Platforma';

              return Container(
                width: width * 0.5, // Ekranning 50% ini egallaydi
                height: 100,
                color: Colors.blue,
                child: Center(
                  child: Text('Platforma: $platform\nWidth: $width'),
                ),
              );
            },
          ),
        ),
      ),
    );
  }
}