I was using MS Excel and a question arose concerning input auto-correction: when is the right time for it?

Some context first: as I'm in France the comma (,) is used as decimal separator. Thus when I enter some data in an Excel cell using the numeric keypad, any stroke on the . (Del) key is automatically replaced by a comma in the entered data, which is good when I'm actually entering a decimal value:

A number in an Excel cell

but no so good if I'm typing, for example, an IP address:

An IP address in an Excel cell

I've experienced the same frustration using some text editors when suspected spelling errors are auto-corrected while I'm typing, but once the phrase is complete the software detects a grammatical error on this auto-corrected word that I have to change back...

Would it not be better to correct what the user is entering when there is more context? For the Excel example the . character could be kept until the input is validated by the user and once it can effectively be evaluated as a decimal. Would it not be better yet to correct the auto-correction if an error is due to an auto-correction?

I'm curious about the best practices to be followed here.

2 Answers 2


Auto-correction shouldn't occur. It takes control away from the user, is often wrong, and is even worse if it's changing the content of the message silently.

You cite localization as one of the area in which it behaves badly. It's also the case with old or dead languages, citations, programming languages, medicine or very technical terms... Actually there are very few cases in which it isn't very annoying.

You just have to look up online the impressive amount of confusion caused by smartphones' auto-correction.

Correction should be optional, and take effect only when the user asks for it.

  • 5
    Agreed! Silent auto-corrections, no thanks. Clear auto-suggestions with quick "correct" action, yes please.
    – Svish
    Feb 25, 2013 at 12:38

This is as far as I can tell not a matter of auto-correction, but rather how you have set up your keyboard/regional/language settings.

I'm on a norwegian keyboard and we too use the comma (,) as a decimal point. The decimal point key on the numpad has a comma (,) printed on it and it will always type a comma (,), no matter what application I use or what kind of field I type it into. To change this behavior I have to change my OS settings.

I'd say this is the proper behavior as well since it would be highly annoying if the key was changing behavior on me depending on context. At least I would find that very unreliable...

For your particular case of typing IP addresses fast, I've always just used the period key with my left hand while typing the numbers with my right on the numpad.

  • On AZERTY keyboards the concerned key actually has a dot printed on it and is a dot for all applications (except Excel, which may be configurable also). But I'm not asking here about this specific point but auto-correction timing in general... Feb 25, 2013 at 12:30
  • 2
    I totally agree with you saying that "it would be highly annoying if the key was changing behavior on me depending on context" BTW :) Feb 25, 2013 at 12:31
  • Aha, I see. Didn't know that!
    – Svish
    Feb 25, 2013 at 12:31
  • 1
    I can't say anything backed by data on that issue, but in my personal opinion I tend to prefer suggested-correction rather than auto-correction since auto-correction in many cases gets things wrong and then you have to fix it. Or you miss the auto-incorrection completely and end up having typed something else than what you thought.
    – Svish
    Feb 25, 2013 at 12:36

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