Is a variable named i unacceptable? [closed]

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Closed 4 years ago.

As far as variable naming conventions go, should iterators be named i or something more semantic like count? If you don't use i, why not? If you feel that i is acceptable, are there cases of iteration where it shouldn't be used?

Answer 1

I tend to use i, j, k for very localized loops (only exist for a short period in terms of number of source lines). For variables that exist over a larger source area, I tend to use more detailed names so I can see what they're for without searching back in the code.

By the way, I think that the naming convention for these came from the early Fortran language where I was the first integer variable (A - H were floats)?

Answer 2

I use i for short loops.

The reason it's OK is that I find it utterly implausible that someone could see a declaration of iterator type, with initializer, and then three lines later claim that it's not clear what the variable represents. They're just pretending, because they've decided that "meaningful variable names" must mean "long variable names".

The reason I actually do it, is that I find that using something unrelated to the specific task at hand, and that I would only ever use in a small scope, saves me worrying that I might use a name that's misleading, or ambiguous, or will some day be useful for something else in the larger scope. The reason it's "i" rather than "q" or "count" is just convention borrowed from mathematics.

I don't use i if:

• The loop body is not small, or
• the iterator does anything other than advance (or retreat) from the start of a range to the finish of the loop:

i doesn't necessarily have to go in increments of 1 so long as the increment is consistent and clear, and of course might stop before the end of the iterand, but if it ever changes direction, or is unmodified by an iteration of the loop (including the devilish use of iterator.insertAfter() in a forward loop), I try to remember to use something different. This signals "this is not just a trivial loop variable, hence this may not be a trivial loop".

Answer 3

As long as you are either using i to count loops, or part of an index that goes from 0 (or 1 depending on PL) to n, then I would say i is fine.

Otherwise its probably easy to name i something meaningful it its more than just an index.

Answer 4

i is acceptable, for certain. However, I learned a tremendous amount one semester from a C++ teacher I had who refused code that did not have a descriptive name for every single variable. The simple act of naming everything descriptively forced me to think harder about my code, and I wrote better programs after that course, not from learning C++, but from learning to name everything. Code Complete has some good words on this same topic.

Answer 5

What is the value of using i instead of a more specific variable name? To save 1 second or 10 seconds or maybe, maybe, even 30 seconds of thinking and typing?

What is the cost of using i? Maybe nothing. Maybe the code is so simple that using i is fine. But maybe, maybe, using i will force developers who come to this code in the future to have to think for a moment "what does i mean here?" They will have to think: "is it an index, a count, an offset, a flag?" They will have to think: "is this change safe, is it correct, will I be off by 1?"

Using i saves time and intellectual effort when writing code but may end up costing more intellectual effort in the future, or perhaps even result in the inadvertent introduction of defects due to misunderstanding the code.

Generally speaking, most software development is maintenance and extension, so the amount of time spent reading your code will vastly exceed the amount of time spent writing it.

It's very easy to develop the habit of using meaningful names everywhere, and once you have that habit it takes only a few seconds more to write code with meaningful names, but then you have code which is easier to read, easier to understand, and more obviously correct.

Answer 6

i think i is completely acceptable in for-loop situations. i have always found this to be pretty standard and never really run into interpretation issues when i is used in this instance. foreach-loops get a little trickier and i think really depends on your situation. i rarely if ever use i in foreach, only in for loops, as i find i to be too un-descriptive in these cases. for foreach i try to use an abbreviation of the object type being looped. e.g:

foreach(DataRow dr in datatable.Rows)
{
    //do stuff to/with datarow dr here
}

anyways, just my $0.02.