Building a Number Guessing Game

Hello Dart enthusiasts! Welcome back to our fun and enlightening journey through Dart, with the ‘30 projects in 30 days’ challenge. Today, we’ll be building a number guessing game.

As we go through this project, I’ll break down the code into smaller chunks and explain each part in simple English, using analogies where possible to help you grasp the concepts more easily.

The Code

Before you begin, here’s the complete code.

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

void main() {
  final random = Random();
  // generate a random number between 1 and 100
  final answer = random.nextInt(100) + 1;
  
  print("I'm thinking of a number between 1 and 100. Can you guess what it is?");
  int guess;
  int numGuesses = 0;
  
  do {
    numGuesses++;
    stdout.write("Enter your guess: ");
    guess = int.parse(stdin.readLineSync()!);
    
    if (guess < answer) {
      print("Too low. Guess higher.");
    } else if (guess > answer) {
      print("Too high. Guess lower.");
    } else {
      print("Congratulations, you guessed the number in $numGuesses guesses!");
    }
  } while (guess != answer);
}

Now let’s break down.

Imports

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

These two lines at the start are importing Dart’s Input/Output and math libraries. You can think of it like bringing your toolbox (IO) and your Swiss Army knife (math) to a repair job.

The main function

void main() {
  final random = Random();
  final answer = random.nextInt(100) + 1; 
}

Our main() function is the starting point of our Dart application, like the ignition switch of a car. We create a Random object to generate random numbers, and answer is set to a random integer between 1 and 100.

Message to the user

  print("I'm thinking of a number between 1 and 100. Can you guess what it is?");
  int guess;
  int numGuesses = 0;

Next, we print out a message for the user and declare two variables: guess to store the user’s guesses, and numGuesses to keep track of the number of guesses the user has made, like a scorekeeper in a game.

The game loop

  do {
    numGuesses++;
    stdout.write("Enter your guess: ");
    guess = int.parse(stdin.readLineSync()!);
  } while (guess != answer);

Here, we enter a loop using do where we increment numGuesses with each cycle. We prompt the user to input their guess, and read it from the standard input (the console). This is akin to asking the player for their next move in a game of chess.

Checking the guess

do {
    //...
    if (guess < answer) {
      print("Too low. Guess higher.");
    } else if (guess > answer) {
      print("Too high. Guess lower.");
    } else {
      print("Congratulations, you guessed the number in $numGuesses guesses!");
    }
  } while (guess != answer);

Finally, we use conditional statements to guide the user to the correct answer. If the guess is lower than the answer, we prompt them to guess higher, and vice versa. If the guess is correct, we congratulate them and inform them of the number of attempts it took. We continue this loop until the guess matches the answer. It’s like playing a hot and cold game, guiding the player towards the treasure based on their proximity.

Conclusion

And that’s it! With these simple steps, we’ve created an exciting number guessing game using Dart. This shows how we can take user input, generate random numbers, and control the flow of the program based on conditions.

Stay tuned for our next project! Remember: coding is an adventure - enjoy the journey!

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