Everybody who has ever seen any C code has

  #define i index

programmed deeply in his brain's CPP.

Using i for loop counter never causes confusion and using index makes the for statement 12 characters longer for no reason.

I'm sure they do, it's not relevant; using short meaningless variables names as a matter of habit eventually always causes confusion because of nested loops. If you can touch type, counting characters is an absurd reason to write obtuse code. Code is read far far far more than it is written; optimize for reading, not writing.

I'm very well are "i" is idiomatic; I still think it's stupid, as are many such idiomatic hangovers. Idiomatic does not mean correct or good, it means popular. Well chosen meaningful variable names are always a plus and are a sign of a programmer that understands code is read far more than it is written and not always by those who know all the little idioms of a particular language.

If you count to 100 or iterate over some array, i, j, k, l are more readable than index1, index2, index3, index4 simply because they are shorter and still mean the same.

And if you iterate over some collections of "meaningful" objects, meaningful names are more readable than either i or index.

It never makes sense to use index over i.

If there were nested loops, I'd use meaningful names, and as a matter of course of using meaningful names, index beats i on a single loop. It's silly to sometimes use meaningful names and sometimes abbreviate because you're too lazy to type.

Of course, these are personal subjective things, but if you allow the habit of abbreviation, it tends to spread where it isn't appropriate, better to simply not do it.

'index' just isn't meaningful. Use actual meaning or use shorthand. Don't waste verbosity.

"index" is very meaningful, it tells me I'm indexing and not counting, otherwise I'd use "count". Confusion between those two often causes off by one errors, so yes it does actually matter and is actually meaningful. You might like "i" or "n" to convey the same meaning, but as I said, I want words not abbreviations.

Of course, it should be `aStreamPosition` rather than `index` - still not `i` ;)