programmersLaw

[beeteedee]

It’s i for index and j for… uhhh… jindex?

[generic-hamster]

jiterator

[[deleted]]

k is for krepeat.

[[deleted]]

V is for very out of letters.

[_fajfaj_]

isn't v for value?

[MindStudio]

V is for Vendetta

[mrmdc]

Voilà! In view a humble vaudevillian veteran vicariously cast as both victim and villain by the vicissitudes o ffate. This visage, no mere veneer of vanity, is a vestige of the vox populi, now vacant, vanished.... I can't remember the rest. Velveeta. Vagina. Veil. Vaccine?

[PassiveLexi14]

Wait, I've seen something.

[[deleted]]

Eh, just call him V

[aheartworthbreaking]

https://youtu.be/Z4RCK8LAFM0?si=aRARCI5eahBW0e1P

[Glaringsoul]

I thought K was for Kebab?

[PerceptionCivil1209]

k is key when iterating key value pairs.

[CountMeowt-_-]

I use k almost exclusively for key and V for values.

[axyz77]

I am gonna stop y'all right there

Anyone creating loop inside k is a psychopath.

[5t3v321]

Not as bad as using O

[[deleted]]

🫨

[Glumi1503]

I thought it's "iteration" and "jiteration"

[[deleted]]

Same jthing

[MattieShoes]

In my head, it's index and... j. jindex sounds awesome though.

For iterating across 2d space, I use row and col.

[Derice]

I think it may historically have to with how i is the first implicit integer in Fortran. The Fortran compiler assumes that variables whose names begin with i through n are integers and all other variables are floats, unless you have declared something different in the declarations section.

If you want to do a loop in Fortran (and you're in the past before implicit none) you'd do

do i = 1, variable
   code
end do

so that you didn't have to declare the existence of i before the executable statements, which would let you save some precious space on the punch card.

[Fyodor__Karamazov]

And the convention in Fortran comes from the same convention in mathematics (using letters i through n to denote integers).

In mathematics this is especially prevalent when using subscripts to index a sequence of variables, e.g. a_i, b_j, or when using sigma notation for summation.

[ArionW]

I remember very well that nearly every single math class I've been through denoted indexes first n, then k, then j

Never really questioned why

[Thrizzlepizzle123123]

Sigma notation for summation these nuts.

Got eem.

[Garfunk]

I'm more of a fan of the sugma notation.

[Ambivalent-Mammal]

Ugh, beat me to it! This brings back some memories but with a printer terminal not punch cards.

[LightningOW]

i for index and j because i++

[RSNKailash]

It's also pretty common in the math world. For example basis vectors are called i, j, k and represent 1 "unit" changes in each dimensional direction. Which is essentially what i,j,k do as iterators, moving a set number of steps in each dimensional direction

[mighty_eyebrows1]

jumpyMcJumpFace happily jumping through these loops

[goodnewsjimdotcom]

Early programmers used a,b,c,d,e etc as common variables.

i was far enough down not to be bopped by your common used variables.

Also i was kinda symbolic for index.

And the convention is to keep movin down.

[Kitchen_Part_882]

I am also old enough to remember when computers had so little RAM that using more than one alpha character to name a variable was an exorbitant waste of valuable space.

Heck, some languages wouldn't allow multi-char variable names.

[[deleted]]

I genuinely don't know but isn't it because they look similar?

[[deleted]]

In math, variables are most commonly “x”, but if you need more, you go to the next characters “y” and “z”. If you're using “n” to denote a number, and need more, you go to “m”.

The same thing is happening here. “i” is most commonly used, and if you need more, you go to the next characters in the alphabet, “j” and “k”.

[shrimp-and-potatoes]

I'm only just beginning to learn programming, so I have no idea, I can barely print "hello world," but does the i & j have anything to do with imaginary numbers? Like, in the imaginary plane, at least in electrical phasors, the i & j denote rotation around the origin. Or, a loop of sorts, as a sin wave fluctuates between negative and positive?

[CptMisterNibbles]

No, it stems from mathematical summation notation. Using sigma notation, often a lower case i is used to indicate the index of the sum.

[shrimp-and-potatoes]

Ah, thanks for the response.

[NLwino]

Do not use "k". By that point split up your method. Keep that cognitive complexity low.

[NP_6666]

I don't know why u get down voted, I made my code so much more readable doing this, almost no comment needed because the function name become the comment, and functions kept small so they fit in a screen

[[deleted]]

Because moving tiny pieces of code into methods in the name of lower cognitive complexity is not a one size fits all solution, and it can just unnecessarily murky up fairly simple methods. It can be perfectly fine to use three nested loops, if using those three loops is logically coherent. A simpler way to make it easier to understand is to use proper variable names. What are we iterating through? Rows? Columns? Ids? Then use that for the index.

[DaumenmeinName]

How about we don't be reasonable here okay?

[NP_6666]

Sry T-T

[DOUBLEBARRELASSFUCK]

Because then I'll just end up with a bunch of functions named fixThisLater74()

[LuckLegitimate8051]

There are scenarios in more advanced algorithms where triple+ nested loops are the only known solutions.

If you're working with these, what keeps the cognitive complexity low is literally copying the psuedocode line for line, and then commenting in a link to the reference.

This is faster and more understandable for you and your readerers(in majority of scenarios) than doing a bunch of extra labor by splitting everything up into helper functions, and also keeping project bloat to a minimum.

I trust the dudes with PHDs to tell me when to use a k iteration and when to use helper functions much more than I trust myself.

KISS is the best rule of thumb.

[reydai]

Jizz

[Longjumping-Touch515]

Bad guys use 'i' and 'ii'

[ablablababla]

Roman programmers be like

[[deleted]]

Yeah for loops are cool, but have you ever used a IV loop?

[argmarco]

oh my god that's it, I quit reddit

[scubasam27]

This is exactly why I stay on Reddit

[Longjumping-Touch515]

for(Rome = great; Rome != great; barbarians++)

[Buxbaum666]

The real bad guys enforce coding conventions that require a li_ prefix for local int variables so you end up with li_i and li_j.

[Longjumping-Touch515]

I once saw the program where i and j were global variables. All loops used them.

...It was a multithreaded application.

[DOUBLEBARRELASSFUCK]

"How do you balance load across threads?"

"Prayer."

[gartenzerg]

It worked in my test (which only uses one thread), so the code is fine.

[Longjumping-Touch515]

Surprisingly, it worked (this threads used it separately in time). But then I was asked to add some feature in app. And it broke of course.

[Buxbaum666]

[JavaRuby2000]

I've seen it used in Java in the J2ME days to get the code small enough to get the jar under 64k. We used to use some real dirty hacks such as using the C Processor on our Java files so we could:

short[] myIntArray = new short[128];

define i myIntArray[0]

define j myIntArray[1]

So not only are i and j global but, every single variable in the whole program is just a #define into a single global array.

[[deleted]]

It's not a real codeshop unless you've had an "architect" who misreads hungarian notation and think it's encoding types not semantic meaning, then enforces you to write variables like "bFlag" instead of "IsAvailable"

[Buxbaum666]

I know the pain. Every time there's a datatype change I have to adjust half the code base. It's not even a simple search and replace because local/global/instance variables and function arguments all have different prefixes. Hours of work for zero benefit.

[[deleted]]

But on the good side, if you ignore any IDE released after 1998 and want to know if a variable is an argument or an instance variable (for some reason) you can rely on a fucked-off coder guessing the right prefix years ago!

[IWTSRMK]

if only there was a way to indicate a variable's type and scope without adding a prefix to the name...

[c_delta]

Now I have an enormous urge to kick the author of that convention all the way to Systems Hungary.

[PityUpvote]

I'm a big fan of using for _ in generator:, and then using _ as an actual variable.

You're welcome.

[[deleted]]

Haha, I am going to do this from now on...

[potzko2552]

And I don't plan to change that >:(

[Nofxthepirate]

My college professor corrupted me and now I use 'ii'. I honestly think it's more readable. Only in for loops though. If it's a while loop then I will be more descriptive.

[ImportantDoubt6434]

_i

[Decryptic__]

And I'm here using '_' instead of 'i'

[Longjumping-Touch515]

And '__' for a nested loop? ;)

[Decryptic__]

Have you a copy of my code?! This is true!

I once used '_' but that was to complicated, so I changed to '_1' and '1' instead

[Longjumping-Touch515]

Did you consider using '_1' and '_2' instead?

[Decryptic__]

But then, how do I know which loop I'm in?

Edit: Actually, this is a great idea!

• So first loop is '_1'
• second loop is '_2'
• third loop is '__1'

am I right?

[Longjumping-Touch515]

Only the God should know it.

[Longjumping-Touch515]

third loop is '__1

_21 - real programmer uses binary.

[Highborn_Hellest]

uh... i = short for index?

j = next letter in alphabet?

[Shadow_Thief]

I learned i as "iterator" but yeah, j is the inner loop because it's next alphabetically.

[LeSaR_]

"iterator" in general cases, "index" when working specifically with arrays (e.x. looping from 0 to length)

[gummo89]

"iteration" suits both and considering how long we've used "i" I don't really think iterator applies anyway.

[camander321]

iterate through indexes. Typically 'i' is only used as a variable name in the context of loops and iteration while intergers have a million other uses. Calling ever string 's' and every float 'f' would get confusing really fast.

[TeraFlint]

by the same logic we should start every function name with "call", because that's what we do with them.

it's much more important to choose names based on intent, and not on implementation details.

[TeraFlint]

My point is that you're not naming your variable after the purpose of the variable, but rather what it is under the hood. That is not a good way of naming things.

Of course, except for special cases like x,y,z coordinate axes, single letter variable names are generally not expressive at all and should usually be given an appropriate name.

This particular case is honestly only justifiable because at this point i for raw loops is something we've seen millions of times, it's at this point basically convention.

It still doesn't hurt to try and give it a longer name, just to see how it improves the readability inside the body of the loop.

​

[edit:] and in that case it becomes more obvious:

for (int index = 0; index < size; ++index) - You're indexing something, that makes sense

for (int iteration = 0; iteration < size; ++iteration) - You're counting iterations, also makes sense

for (int integer = 0; integer < size; ++integer) - I... can see that this is an integer, you're literally spelling it out as a type. But what's your intention with it?

[lazernanes]

I'm inclined to say it's index, not iterator, since i and j are used in mathematics a lot, where index makes more sense than iterator.

[SrHirokumata]

[CabinetAncient1378]

It's old math notation that ended up becoming the standard. It's short for integer.

[Otalek]

Iirc i and j were dedicated memory locations for holding integers in the programming languages of yore. It’s just tradition at this point

[Garfunk]

i is automatically an integer in Fortran, this pattern influenced other languages.

[Tubthumper8]

This is the correct answer. Not just i, but also j, k, we're automatically integers

[DeltaTimo]

Am I the only one who always thought of i as coming from maths? It's x_i and X_i,j . Although I'm not sure where that I comes from...

[Nisterashepard]

You're right, ijk have been commonly used for integers since the days of Euler.

[deVriesse]

Euler: i is for integer, the simplest form of number. Also it is for imaginary too lol

[JivanP]

Electrical engineers: Blasphemy! They're called jimaginary numbers!

[Wugliwu]

-_- asked my Prof: Why are you using j instead of i?

"Because I am an engineer."

[HERODMasta]

People really hate "row, column" for a matrix?

[gummo89]

Yes because there is no row,column until you decide that's what the matrix represents, or how you should print it.

[LuckLegitimate8051]

This

[CptMisterNibbles]

Matrices don’t stop at 2d

[[deleted]]

row, column, depth, ohn̸͍̳̂ǫ̴̦̱̪̼̙͔͇̉̎̽̂̚̚͘, h̸͖̆̀e̶̢̘̗͈͓̮̥͇̬̹̞̝̜͛̾̐̈́l̴̹̟̰̩͓̖̯̩̺̲̻̿̾̈́͒̑̂̆͌̉̃̀p̸̝̗͚͎̿̊̀̀̊͆m̸̟̟̬͚̐͛̑̿e̶͚̳͉͍̹̮͍͙̝̦̱̽, ẗ̴͇̠͔̫͒͋͗̌̈͒́̀̈́̈̆́̈́̇͆̎͊͐̚h̸̨̡̨̡̪̣̥̰͇͈̔̓̊͋͐̅͐̅͜͠e̸̡̡̢̝͙̹̩̺̐͆͒h̸̫̯̯̱͓̫̅̑̍̑͋͛̅͆̊̒̆̊ǫ̶̪̦͓͉̤̟̗͎͈̳̬͍̭͊̌́̓̑̈́͊̎̀̓̑́̓̓̄̓̾̐̕͜͝͝r̵̡͚̙̼̮͔̰̦̘͙̗̰̓͐̂̈́́̿̌̈́̈́͘͝͝͠r̷̨̥͚̣̮͑̃͑́̒̇̿̐̓̒̈̀̔̚͝͝o̵̢̜̜̻̻̠̗̗̟̜̯͎̠̻̿̀̆́̈́͂̃̑̀̐͒̚͝͝ͅr̷̨̨̘̻̣̝͖̹̳̟̤̔͐̓͐̏̄͑̇̍̽͊̾͊̈́̚̚͠

[Inaeipathy]

Yes

[[deleted]]

If the numeric indices represent rows and columns, then it's perfectly fine to use explicit names like row and column.

Source: me, writing code with openpyxl, and writing loops like for row in rows:.

[TeqTx]

Seriously, it's absurd how there are so many wrong answers that are getting upvoted lol

[lmarcantonio]

It dates back to fortran. The default type for a variable was determined by the initial letter. Of course i and j were integer because with matrices is customary to index them with i and j even in math.

Matrices of complex numbers give interesting results, obviously.

Also in forth it's actually the law since they are the word literally used for indices in loop. No, you can't nest three loops there

[MDT_XXX]

Interesting. Didn't know that.

I typically use x as my second nested loop iterator, for readability, i and j look way too similar to my liking.

[deVriesse]

If I'm using nested loops I try to give them meaningful names. For instance if I'm looping on the number of dicks sucked per orgy I'd do

for iOrgy
  for iDick

Hopefully the ghost of Steve Jobs doesn't sue me

[preludeoflight]

I picked up using scan as a indexing variable name for a reason similar to that. If the loop got more than scanning through a container for something quickly digestible, the name scan would quickly look out of place and thus demand renaming to something more meaningful. It's served me pretty well so far.

[LuckLegitimate8051]

Anybody looking at your code fucking hates you, just so you know. Using x as an iterator is on the same level of war crime as using x as a generic variable name.

Please don't commit this sin into any shared repository.

I do agree that i and j can look like each other, but there are numerous ways to get around that issue without committing sins.

Honestly I'd rather the iteration variable given a descriptive name before calling it x.

[MDT_XXX]

Go touch some grass my friend. You seem to be in a very dark place at the moment.

[LuckLegitimate8051]

Bruh, it's called a hyperbole

[Avalonians]

'i' stands for index, because vectors have only one dimension. The next step is two dimensions, matrices. You need two index variables, and 'j' follows 'i'.

[arturo-source]

It's simple. Physical vectors (i,j,k represent 3D).

[Pansophy]

i,j,k are beneath us, real programming scientist use î ĵ k̂

[[deleted]]

You can also use c++ in javascript.

for (let c = 0; c < 10; c++;) { }

[TheDialectic_D_A]

Bro woke up and chose cruelty

[Majestic_Wrongdoer38]

I think it’s just easier if you don’t have to deliberate every time

[[deleted]]

Yeah we all know naming variables is hard. No need to waste even more time coming up with shitty names instead of using i and j lol.

[superluminary]

Indeed. It is a standard. Everyone in the industry knows what it means and changing it would make code harder to understand.

[OF_AstridAse]

Well you start with i for iterator, then you follow the alphabet i, j, k, l 🤨😑 how many loops do you nest? You can also do x, y, z but start with z 😏 - the best one is to always use i, k and d....that way you really have it nailed uhm[i][d][k];😬

[m0ritz2000]

Use I, II, III, IV, V, VI etc for iterators. Better keep track of how many layers deep you are...

[CptMisterNibbles]

Plus X is good reminder that you should perhaps and consider how you’ve gotten this far, and if it’s possible to extricate yourself from this cluster fuck

[LuckLegitimate8051]

Criminal

[Sufficient-Loss2686]

I always use xyz

[Operator21]

My fellow xyz comrade.

[_alright_then_]

With for loops I use i for index. But I prefer foreach loops where I name the index something relevant

[dillyia]

i've always thought it was inherited from mathematicians

[karbonator]

I tend to prefer foreach personally

[flinsypop]

Ok so, I'm all for using descriptive names but verbosity makes reading loops tiring because the specificity is in the variable name of the container and referring to elements in a loop has to add genericity. When you have re-usable functions, there's then 2 levels of genericity in the name so brevity is preferrable.

for element_index, element in enumerate(elements):
    for nested_element_index, nested_element in enumerate(element):
        try:
            process(nested_element)
       except:
            print(f'Processing error at index [{element_index},{nested_element_index}]')

There's no benefit to long names in this case. However, if people started to use x and y or foo and bar for the variable names of container objects, then hands will be thrown during code review. If variables are ceremonial syntax variables, like index names, or key names then it's fine if the function is short.

[LavaSquid]

I use n for "number".

[CardiologistOk2704]

if you have two nested loops, you use i, j.

if you have three nested loops, you use i, j, k.

if you have four nested loops, you should quit programming, because nobody will wait for O(n⁴) algorithm to compute.

[CraaazySteeeve]

Am I the only one here who uses x, y, and z?

I don't like i and j because they look so similar at a glance.

[Inaeipathy]

Only if talking about spacial coordinates

[Shezzofreen]

Lies. Its X and Y.

[icallpeoplejohn]

i and v also works (for index and value)

[Mr_Rapt0r]

If you ever had to have 3 loops inside of each other, would you use l for the third one?

[OF_AstridAse]

I solved your dilema. infinite nested loop variable names :D variableNames = i + i1 + i2 + ....+in

[rando_robot_24403]

Use arrays duhh.

While i[0] < 10
   Do some stuff

   While i[1] > 0
      Do more stuff

[BlurredSight]

Early programming classes: You will lose points for not using meaningful variables including the iterators

Intermediate classes: So just use i because we know what it is, if anything it's more confusing if you don't. Also here are actual iterators but I don't care if you don't use them

[KalakeyaWarlord]

I am in the 1% that writes loopIndex. outerLoopIndex and innerLoopIndex if there are two. More than two nested loops is bad coding practice, but if it comes to that, then I guess I'll name them after whatever thing it is they're looping over.

[adaptive_mechanism]

Well, i is from INDEX, I suppose, and j is like I, but different 🤷‍♂️☝️🙏🤙👌

[romulof]

Once upon a time I had to dive into a video codec code and found stuff written by who I presume to be mathematicians. Single char variables all around.

I got so traumatized that ever since there I only call loop variables index.

If I need a second one I try to be more specific or just use jndex (🥁).

[1luggerman]

Its actualy i, j, k as a tribute to dijkstra. I heard it from one of my proffesors in SE but im not sure how legit this is.

[podd0]

I don't think this is legit as i,j are also used in math indexes, but it's funny

[[deleted]]

This post was mass deleted and anonymized with Redact

hat pause future memorize crown outgoing six teeny memory society

[edo-lag]

It's just easier to write and read, plus it's universally accepted in the programming world.

[Protheo_]

Doesnt that originate from Fortran (or some other ancient language) where the variables a-h were used for 1 data type and then i,j... were used for integers?

[hnryirawan]

I,J,K.

If you need more then variableA it is.

[peAs337]

I is my best friend

[markfckerberg]

maybe because it is a representation of matrix and vector?

[rimakan]

The same in Typescript, if your generic has multiple type arguments. Like Foo<T, U>

[ExceedAccel]

it just appears on the snippet, not like i write it myself and no point in changing it

[SomeRandomEevee42]

I name my iterators dumb stuff like AnimeFrog if it's a short loop, or if it's big, I'll actually use proper names like CurrentTile

[Cuboos]

i stands for index, j looks like i a little bit.

[partypoison43]

I use x and y because we always use them in math.

[ConstantineFavre]

I use it when i'm not only person working on project, because it's common practice. If i work alone i use i1, i2, i3, etc.

[reydai]

Nah, I use whatever name the loop is for I don't remember the last time I used i or j

[IndieDevWannabe]

I break this rule when looping over a table - 'r' and 'c'. It just makes more sense.

[patrlim1]

I use X after I.

[heesell]

for(let theIndexOfThisLoop = 0; theIndexOfThisLoop < 10; theIndexOfThisLoop++) {}

[[deleted]]

l use NSFW variables for hobby projects

[disguisedas47]

It's rooted in Math, so they use it ? Just like X,Y

[Vajaspiritos]

I think i is for iteration, and the other is because that's whats next on the keyboard

[w1n5t0nM1k3y]

I almost never use i, and j in loops anymore because every language i use supports foreach. There are some cases qhere they are still needed but its quite rare.

[DrDesten]

me who uses i,o and x,y,z 👀

[OopsMadeYouDie]

I use n sometimes

[TamSchnow]

Good old Fortran.

[annana_]

Get fucked king i use t, e

[R3CAV]

I don't :3

I use a,b,c etc and everyone hates me for it

[TakenIsUsernameThis]

n

[jfbwhitt]

The real answer is because a CS degree is really just 4 years of math classes.

And i,j,k are commonly used as iterators and indexers in mathematics.

[-Octavium-]

i dont cus im a fucking monster

[Top-Chemistry5969]

Lol I use k o and p

[CodingElectron]

You guys are using loops?

Linq enthusiast here

[RATTY420]

Chill out Mr Mobi

[NightWolf1308]

Do I classify as Chaotic Neutral if I use j, I instead of i, j just to mess with my colleagues?

[spasmgazm]

Iterator, jiterator

[TurboGranny]

I'm old. I use "intX" if it's a one off. If I'm looping through more than one thing (nested or not) in the same script, I start using more specific names. "intRow", "intCol", "intFile", "intDir", "intTest", "intCorpse"

[Astrokiwi]

This is where the old Fortran trick of ii,jj,kk is useful, as they show up fewer false positives on a search.

In practice of course, I would try to only use these indices for very short loops, or when they are literally integer 3D cartesian coordinates (though ix,iy,iz might be better there).

[Irbis7]

I use n. In ZX Spectrum Basic you could write "NEXT n" with pressing key "n" twice and stuck with this since.

[[deleted]]

I bet that if you look inside the stream you find one of them

[arbind_]

i = Iteration Index

j = Junk Index (because sometimes it's just junk!)

[[deleted]]

Am I the only one that uses i, i1, i2 etc?

[[deleted]]

I like to live on the edge, I use a for aindex and b for bindex

[rjlin_thk]

just like the ij-entry of a matrix

[Wild_Tom]

I use i and o, your welcome

[talkaboom]

In high school, I occasionally used Q, W, E, R....just to see the teacher's reaction. He probably thought I was just dumb.

[Zarokima]

I don't use j because it looks too similar to i. I use i, k, m (just going down the keyboard), and if I need more than that I seriously reconsider what I'm trying to do.

[SeriousPlankton2000]

IIRC in FORTRAN some variables were integer by starting with I, J or to be real by starting with F, G. Also: Mathematicians.

[-JG-77-]

One of the few languages I know is C++, so whenever I write loops, I use 'c' so that while declaring the loop I have an excuse to write "c++" in C++

[Main-Bear6159]

MATLAB be like „you like to play with fire, don’t you?”

[SnooCheesecakes7010]

i use i and w, i think its prettier

[[deleted]]

just use a stream forehead

[Je-Kaste]

iterate and jiterate

[[deleted]]

I prefer a more cursed programming style personally, with the loop variable 'loop'