How to return two value from a function in dart?-CodePudding

here is my code

import 'dart:io';
import 'dart:math';

void main() {
  bool flag = false;
  for (int i = 0; i < 100; i  ) {
    gameCode();
    if (userNumber == computerNumber) {
      flag = true;
      break;
    }

  }
}

int randomNumber(number) {
  Random randNumber = Random();
  int random = randNumber.nextInt(number);
  return random;
}

gameCode() {
  int computerNumber = randomNumber(9);
  print("start guessing the number : ");
  int userNumber = int.parse(stdin.readLineSync()!);
  if (userNumber == computerNumber) {
    print("You got it");
  }
}

in this code you can see gameCode function. in that function there is two value that i need to use in main function.so how do i return those two keyword from that function ?

//userNumber // computerNumber

this is the variable that i want to return from that code

CodePudding user response：

Dart does not support returning multiple values in the current latest version. I would in your case recommend creating a class for the specific purpose of define the result from gameCode(). So something like this:

class GameCodeResult {
  int userNumber;
  int computerNumber;

  GameCodeResult({
    required this.userNumber,
    required this.computerNumber,
  });
}

Which we can then use like this in your program:

import 'dart:io';
import 'dart:math';

void main() {
  bool flag = false;
  for (int i = 0; i < 100; i  ) {
    GameCodeResult result = gameCode();
    if (result.userNumber == result.computerNumber) {
      flag = true;
      break;
    }
  }
}

final _random = Random();
int randomNumber(int maxNumber) => _random.nextInt(maxNumber);

GameCodeResult gameCode() {
  int computerNumber = randomNumber(9);
  print("start guessing the number : ");
  int userNumber = int.parse(stdin.readLineSync()!);

  if (userNumber == computerNumber) {
    print("You got it");
  }

  return GameCodeResult(userNumber: userNumber, computerNumber: computerNumber);
}

Note, I also fixed your randomNumber() method since it is not recommended to generate a new Random() object for each new random number you want. We should instead reuse an instance of Random in our program.

CodePudding user response：

Dart not support return multiple values in function, you can return it with array, map, or you can use third lib tuple

CodePudding user response：

Please refer to below code

import 'dart:io';
import 'dart:math';

void main() {
  bool flag = false;
  for (int i = 0; i < 100; i  ) {
   Map<String, dynamic> res = gameCode();
    print(res);
    if (res['user_number'] == res['computer_number']) {
      flag = true;
      break;
    }

  }
}

int randomNumber(number) {
  Random randNumber = Random();
  int random = randNumber.nextInt(number);
  return random;
}

Map<String, dynamic> gameCode() {
  int computerNumber = randomNumber(9);
  print("start guessing the number : ");
  int userNumber = 
    int.parse(stdin.readLineSync()!);
  if (userNumber == computerNumber) {
    print("You got it");
  }
  return {
    "computer_number": computerNumber,
    "user_number": userNumber,
  };
}