Bad Case #1: so close but you're off by one

 Alrighty, so I've been looking at stuff like bad practices or pitfalls in programming and thought, why don't I add stuff I find to this place?

my regular schedule is still pretty disrupted but it will resume soon(ish) but I'd like to introduce Bad Cases where I talk about the various bad things you could do when coding.

Anyways first one is gonna be off by one errors.

Off-by-one errors are a pretty common issue in programming, especially when you are new or your brain is fatigued. I had to learn what they are, why they occur, and how to avoid them the hard way with practical examples and practice.

so what is an off by one error?

An off-by-one error occurs when a loop or iteration executes one too many or one too few times due to incorrect boundary conditions or index calculations.

or atleast that's the proper definition.

basically its when you try going through a set of numbers and count like a human instead of a computer.
In programming you learn that you have to start from 0 usually, lets say you want to find the range of numbers 1-10, one would think your could just do:

1 2	for i in range(1, 10): print(i)

but unfortunately that would just give you 1-9, gotta use 11

1 2	for i in range(1, 11): print(i)

that's one example, another common one happens in arrays, take a look:

1 2 3

my_list = [0, 1, 2, 3] for i in range(len(my_list)): print(my_list[i])

Remember gotta start from 0, this array looks like its 4 things and it is but for a computer you have the 0th, the 1st, the 2nd and the 3rd
This loop correctly prints all elements in my_list. However, if the loop range is range(len(my_list) + 1), it will result in an IndexError because my_list[4] or the 4th thing, it ends on the 3rd thing which is 3 does not exist.


Common Causes of Off-by-One Errors
1. Misunderstanding Loop Bounds

A common source of off-by-one errors is the confusion between zero-based and one-based indexing. In Python, lists are zero-based, meaning the first element has an index of 0. Misinterpreting this can lead to errors if you assume the first element starts at 1.

2. Misuse of Conditional Statements

Incorrect conditional statements can result in too few iterations or even infinite loops. For instance, using <= instead of < can iterate one extra time.

3. Manual Calculations

Manual calculations for loop boundaries or indices can introduce errors, especially if you miscalculate the start or end of a loop. Incorrect calculations often lead to off-by-one errors.

How to Avoid Off-by-One Errors
1. Clear Requirements

Ensure you fully understand the loop requirements: determine the exact number of iterations and clearly define the start and end of the loop.

2. Consistent Indexing

Stick to one type of indexing throughout your code. Since Python uses zero-based indexing, it’s best to maintain this consistently to avoid confusion.

3. Thorough Testing

Write tests for boundary and edge cases to catch off-by-one errors. Use debugging or for us newbies, the magical print statement between every line to verify that loops iterate correctly and indices remain valid.



well anyways thats pretty much what I got for y'all, so Imma end this bad case here, I plan on using whats left of this week and all of next week to see what other type of junk I could post on here, maybe I'll try news articles or reviews or something but I generally don't like those types of things so idk.

i also need to figure out this SEO stuff too, I'm hearing that I should use ChatGPT but I don't know if I should abuse my father like that, but meh, we will see.

anyways till next time

~~Justin Case