There are lots of explanations here and there, including this one, that let me think the answer is yes, it is wrong. However, I'm currently reading the preface of a PDF book and in a few lines I've encountered three times the word "then" with the feeling it should have been "than". Since the book seems quite serious, I can't really believe that an error like this could be in the very first sentences of the preface, hence the question.

Extract from Object-oriented Programming with ANSI-C:

Object-oriented programming is the current cure-all — although it has been around for much more then ten years. At the core, there is little more to it then finally applying the good programming principles which we have been taught for more then twenty years.

Do we agree that the word then that appears three times in bold in this citation is wrongly used and should be replaced by than?

If we do, could you see a reason why then is used instead of than ? Could it be some sort of local variance?

  • 4
    This is either three mistakes or three typos in a row. Commented Sep 30, 2016 at 9:56
  • Ouch. Don't buy that book.
    – gnasher729
    Commented Nov 5, 2019 at 20:07

2 Answers 2


In all three cases, it's either a typo, or someone is very wrong in their use of than.

We don't have to get to the meanings to find out the mistake. than is a preposition and sometimes a conjunction. then is almost always an adverb. All your empty slots, should we have been filling them with either then or than, require a preposition.

If we resort to meaning, than is used to demonstrate contrast.

For years, people have been trying to be more awesome than me.

then either refers to a specific time

Obviously, we did things right back then.

or is used for introducing subsequence.

Then, I tried to convince him that I'm wrong.

Mistaking than for then or the vice versa is not uncommon on the 'Net, notably.

  • Thank you for this detailed answer. I'm used to seeing multiple mistakes on the 'Net but I have a high trust factor in the grammar of the books I read, including this kind of document. I'll mail the author :-)
    – Tim
    Commented Oct 3, 2016 at 5:57

This is definitely a very sloppy mistake. Then and than, while similar looking and sounding words, have totally different meanings, and should never be substituted for one another.

However, it's a relatively common mistake in casual usage, especially on the internet, and especially when taking dictation. A number of accents and dialects reduce the vowel sound in both words.

It's normally caught by even a simple context-sensitive grammar checker, suggesting that this book was not very well edited.

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