A comment in some vb.net code is as follows:


Meaning, (the following bit of code) checks if the current time matches the configured one.

According to what I learnt from textbooks etc, the か in there should be a かどうか, because theres no question word in the sentence, making this incorrect Japanese. Is that right? I'm confused because this was written by a native Japanese speaker.

  • 2
    You tagged this casual, but I don't think that applies here.
    – user1478
    Sep 28, 2017 at 22:06

2 Answers 2


That sentence is grammatical and natural-sounding. In fact, all of the following patters are grammatical.

1) 「Mini-Sentence + か + 確認{かくにん}する」

2) 「Mini-Sentence + か + を + 確認する」

3) 「Mini-Sentence + か + どうか + 確認する」

4) 「Mini-Sentence + か + どうか + を + 確認する」

1) and 2) are used (far) more often than 3) and 4) as using 「どうか」 could at times make it sound a bit wordy and slightly too conversational in business situations.

Versions using 「を」 would sound a tiny bit more formal than those without it.

  • Interesting to hear those are all grammatical too, which poses the question why do text books assert that かどうか should specifically be used when there is no question word, if in fact it doesn't matter?
    – Pootan
    Sep 29, 2017 at 2:59
  • 1
    @user3801230 Are you sure it's not one textbook rather than textbooks? Of the books I checked just now, none of them said it was obligatory. For example, in its entry for か(どうか), A Dictionary of Basic Japanese Grammar says "When the optional どうか is used, the embedded question has to be a yes-no question. If it is not used, then the question can be either a yes-no question or a WH-question." (p.169)
    – user1478
    Sep 29, 2017 at 6:20
  • To be more accurate, yes one textbook and a website: Genki, an integrated course in elementary Japanese (vol 2, chapter 20), and when I googled I looked at a page about it on japanese-adventure.com
    – Pootan
    Oct 1, 2017 at 0:58

It is the question marker か. Think of it like this, posed as a normal question:

現在の時刻が設定時間と一致している → Does the current time match the configured time?

Then you're just adding 確認する to that, making it

Check "does the current time match the configured time?" → Check if/that/whether the current time matches to configured time.

This か is very close to かどうか. In fact, there would not be much semantic difference if かどうか were used here. It's equivalent to the difference between saying "check whether" and "check whether or not" in English.

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