How to build Cows & Bulls – the numeric Wordle!

What is Cows & Bulls?

Cows & Bulls is a classic code-breaking game. It predates both the famous board game Mastermind and the game which is a craze these days, Wordle! There are multiple variations but in its simplest one, you need to guess a secret four digit number picked by the computer. To learn about the history of this game, click here.

RULES:

1. All four digits of this secret number are different.
2. Each digit can be any number from 0 to 9.
3. You start with a random four digit number as a guess.
4. If a digit from your guess matches but is not in the correct position in the secret number, it is a "Cow".
5. If a digit matches and is in the correct position, it is a "Bull".

GOAL:

To get four bulls in 7 guesses or less!

EXAMPLE:

1. Secret number: 4596
2. Guess: 5193
3. Result: 1 bull and 1 cow (5 is a cow and 9 is a bull)

Demo & Screens

Here is a quick demo of the app!

The app has three screens:

1. Home screen - From here, you can either:
   1. start a new game
   2. check your results (they are stored locally and so are specific to your device. If you play this game on two different mobile devices or on a desktop browser, your scores will not be the same across these devices)
   3. navigate to the How to screen to read the rules
2. How To Play screen - Includes all the rules of the game including examples
3. Game screen - This screen is broken down into two main sections:
   1. Guesses list where you can see all the guesses in a given game with the counts of cows and bulls in each guess
   2. Number entry. A few features that stand out:
      • The text boxes aren't really text boxes. They are labels.
      • There is an on-screen keyboard. This is because there were certain restrictions I wanted to place. For example, once a digit is clicked, it shouldn't be available for selection again in the same guess. Plus, when you click on a text box and the device's keyboard shows up, it kind of moves the app up and isn't the best user experience. And this is why I used labels instead of text boxes.

Cows & Bulls app sample

Two versions (MSAPP file, and ZIP package for import) of this game can be found here.

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