Snake size not increasing after eating food

[shivajikobardan]

TL;DR

snake game javascript

Relevant code:

if (food.x === snake[0].x && food.y === snake[0].y) {
    // increase the size of the snake
    snake.push({
      x: snake[snake.length - 1].x,
      y: snake[snake.length - 1].y    });

where snake is an array of objects. Each object is x and y coordinates of snake position and food is an object with x and y coordinates randomly placed.

Here's the full code:

 

[pbuk]

First I strongly encourage you to stop scattering variables representing state around in your code (e.g. let d half way down). Gather all of these into a single object declared before anything else:

const state = {
  // Current direction of the snake (could have a better name like `currentDirection`).
  d: 'right',
  // Array of coordinates of the elements of the snake.
  snake: [{ x: 15, y: 15 }],
  // ...
};

This will save you a LOT of time, but more importantly it will also save time for anyone else trying to help you.

Now as to your question think about where you want the coordinates of the new element to be after eating food to be. Then look at x: snake[snake.length - 1].x and think where you are actually setting the coordinates to be.

 

[shivajikobardan]

@pbuk just humble request, is it illegal to share the code in this forum or something? I've tried a lot and failed. So, would not it be good to share the code with me now? Or is stackoverflow the only place?
Those who are willing to learn will still learn even if you share code, those unwilling to learn won't even if you don't. Not sharing code in a programming problem where someone has gave that much try is just funny.

 

[Wrichik Basu]

@pbuk just humble request, is it illegal to share the code in this forum or something? I've tried a lot and failed. So, would not it be good to share the code with me now? Or is stackoverflow the only place?

You are asking us to correct the logic of your program. Well and good. We can help with that, and @pbuk did help with that:

Now as to your question think about where you want the coordinates of the new element to be after eating food to be. Then look at x: snake[snake.length - 1].x and think where you are actually setting the coordinates to be.

Now, you are basically expecting to be spoon-fed the correct version of the code instead of being given hints where to find the issues. This is something we prefer not to do. In my personal opinion, in the case of programming, you will learn a lot more by debugging your code yourself with occasional hints from others rather than someone just giving away the full code with necessary changes made, unless the error is not logical but syntactical. That's how I learnt programming myself.

 

[shivajikobardan]

looks like I should be paying to a tutor instead :D thanks for your responses.

 

[shivajikobardan]

btw stackoverflow and chatgpt both thinks the code should be working. I also don't see anything wrong with the code even though I've read your comments.

 

[Mark44]

Thread title: Snake size not getting increased after eating food

btw stackoverflow and chatgpt both thinks the code should be working. I also don't see anything wrong with the code even though I've read your comments.

Whether you see it or not, the thread title you chose indicates that you know something is wrong with the code. The fact that ChatGPT and some random users on stackoverflow think that the code should be working does not reflect well on them.

Now as to your question think about where you want the coordinates of the new element to be after eating food to be. Then look at x: snake[snake.length - 1].x and think where you are actually setting the coordinates to be.

This is a very strong hint.

In my personal opinion, in the case of programming, you will learn a lot more by debugging your code yourself with occasional hints from others rather than someone just giving away the full code with necessary changes made, unless the error is not logical but syntactical.

I couldn't agree with this more. Seeing someone do something and doing the same thing yourself are two entirely different things. And to elaborate, one aspect of effective debugging is to predict beforehand what some section of code will produce, and then using the debugger to verify that prediction or tell you that for some reason, your prediction was incorrect.

 

[Wrichik Basu]

btw stackoverflow and chatgpt both thinks the code should be working.

ChatGPT is not even supposed to check your code.

I found your question on Stack Overflow: https://stackoverflow.com/q/75368306/8387076

One user commented that it works for them. They posted a link, where I see just a white screen. No HTML, no CSS and only some JS. A white screen. No snake. No boxes. Doesn't even make sense.

The MWE you posted on SO isn't even enough to reproduce what you are trying to do.

Also, there is a difference between "should be working" and "is working".

I also don't see anything wrong with the code even though I've read your comments.

From the output of the code sample you posted in the OP, I can confirm it's not working, even though I am illiterate in JS. In addition to the fact that the snake size doesn't increase, if the snake goes out of the boundary, it never returns.

If everything is fine, why post a thread here and a question on SO?

 

[Vanadium 50]

chatgpt

I use fortune cookies. Tasatier and no less reliable.

 

[Jarvis323]

The code has a few problems.

First, you only ever move the first segment of the snake. And second, when you grow the snake, you need to add the new segment to the position where the last segment was before it moved. And then what happens if the snake goes out of bounds or self intersects?

You might try to get some paper and pencil and draw the snake, and then try to think through what things should happen step by step when it updates. Then maybe try putting those steps in comments first, and then carefully add the code to implement the steps.

Here is an example with pseudocode of how your draw function could work, if you get stuck:

Spoiler

One way to think about it: move each non head segment to the position of the segment in front of it, move the head segment in the current direction, and if it eats food, add a new segment where the last one used to be.

// save last segment position before moving it
lastSegPrevious = segments.last

// move each non-head segment to the position of the segment in front of it
for( i = N-1; i >= 1; --i)
    segments[ i ] = segments[ i - 1 ]

// move the head in the current direction
segments[ 0 ] = += d

// What if it goes out of bounds?
<?>

// check if snake eats food
if segment[ 0 ] == foodPos
    // add new segment where the last segment used to be
    segments.push( lastSegPrevious )

// Self intersection?
<?>

draw everything

 

[shivajikobardan]

@Wrichik Basu impressed by your stuffs(apps and github). Would love to hear how you achieved this? How do you achieve problem solving logic?

 

[shivajikobardan]

The code has a few problems.

First, you only ever move the first segment of the snake. And second, when you grow the snake, you need to add the new segment to the position where the last segment was before it moved.

You might try to get some paper and pencil and draw the snake, and then try to think through what things should happen step by step when it updates. Then maybe try putting those steps in comments first, and then carefully add the code to implement the steps.

Here is an example with pseudocode of how your draw function could work, if you get stuck:

Spoiler

One way to think about it: move each non head segment to the position of the segment in front of it, move the head segment in the current direction, and if it eats food, add a new segment where the last one used to be.

// save last segment position before moving it
lastSegPrevious = segments.last

// move each non-head segment to the position of the segment in front of it
for( i = N-1; i >= 1; --i)
    segments[ i ] = segments[ i - 1 ]

// move the head in the current direction
segments[ 0 ] += d

// check if snake eats food
if segment[ 0 ] == foodPos
    // add new segment where the last segment used to be
    segments.push( lastSegPrevious )

draw everything

thanks for the good stuff.

 

[Wrichik Basu]

@Wrichik Basu impressed by your stuffs(apps and github). Would love to hear how you achieved this? How do you achieve problem solving logic?

My school gave a hell LOT of programming problems. And I solved them all by myself. That created the base for programming logic.

 

[shivajikobardan]

My school gave a hell LOT of programming problems. And I solved them all by myself. That created the base for programming logic.

Can you share those problems? I'm having hard time findin problems that are not too easy and not too hard. Codewars 7kyu problems are even harder for me. Indian programming books don't have proper exercises.

 

[Wrichik Basu]

Can you share those problems? I'm having hard time findin problems that are not too easy and not too hard. Codewars 7kyu problems are even harder for me. Indian programming books don't have proper exercises.

Those are Java programs, but anyway, I will get in touch with you via PM after I polish the document a bit.