12-hour to 24-hour clock conversion

  • I want to convert a 12-hour clock to 24-hour clock up to the ms.

    Example: Today is 12:00:00:001 AM and it’s raining.
    Output: Today is 00:00:00:001 and it’s raining.

  • @Sophia-Cruz

    check regular expression in replace dialog and use
    find what: (\d{1,2})(:\d{1,2}:\d{1,2}:\d{1,3}) AM
    and replace with 00\2

  • @Ekopalypse thanks for the answer but what if it’s multiple numbers in AM and PM, and the separator will be from . to :? Regex won’t work for other numbers.

    Example: PM -> 13:25:31:934 AM -> 04:02:28:421 PM -> 21:55:03:732

  • @Sophia-Cruz

    would you mind clarifying the exact format of your data as this is essential for
    regular expressions to work correctly. For example, in the previous request you used :
    to separate time fields and now you are using a dot.

  • @Ekopalypse I’m sorry I wasn’t clear with my question. I’m really looking for an answer for my 2nd request. I posted the 1st one because I was still trying different regex which would answer my 2nd request and I was hoping I could formulate something with the answer that you provided.

  • @Alan-Kilborn thank you for this link but I already tried the answers provided but I was only able to convert am up to minutes using . as a separator.

  • @Sophia-Cruz

    It wasn’t for you, it was for future searchers of this site that may find this topic when what they are really looking for is the other way around. :)

    BTW if Eko doesn’t solve your problem here in a reasonable amount of time, I’ll jump in. :)

  • @Alan-Kilborn

    Alan, LOL, please feel free to do so - you are much more in this regex then I’m.

  • @Sophia-Cruz

    This seems to do it:

    Find: ^(?:(01)|(02)|(03)|(04)|(05)|(06)|(07)|(08)|(09)|(10)|(11)|(12))\.(\d\d)\.(\d\d)\.(\d{3}) (?:(A)|(P))M
    Repl: (?{12}?{16}00:12)(?{1}?{17}13:01)(?{2}?{17}14:02)(?{3}?{17}15:03)(?{4}?{17}16:04)(?{5}?{17}17:05)(?{6}?{17}18:06)(?{7}?{17}19:07)(?{8}?{17}20:08)(?{9}?{17}21:09)(?{10}?{17}22:10)(?{11}?{17}23:11):$13:$14:$15
    Search mode: Regular expression

    I tried to be “fancy” and do the “AM” and “PM” part with “named groups” so that the replacement is more “readable”, but I ran into some trouble with that. If I get it working, and it truly is more readable, I may post that as well…

  • I got it to work with named groups. The problem was, and it makes it less elegant, is that mixing numbered and named capture groups seems to mess things up. So I had to artificially name group # 1 as “one” instead of just using its number. I’ll let the reader decide if this version is more readable than the previous:

    Find: ^(?:(?<one>01)|(?<two>02)|(?<three>03)|(?<four>04)|(?<five>05)|(?<six>06)|(?<seven>07)|(?<eight>08)|(?<nine>09)|(?<ten>10)|(?<eleven>11)|(?<twelve>12))\.(?<mins>\d\d)\.(?<secs>\d\d)\.(?<ms>\d{3}) (?:(?<am>A)|(?<pm>P))M

    Repl: (?{twelve}?{am}00:12)(?{one}?{pm}13:01)(?{two}?{pm}14:02)(?{three}?{pm}15:03)(?{four}?{pm}16:04)(?{five}?{pm}17:05)(?{six}?{pm}18:06)(?{seven}?{pm}19:07)(?{eight}?{pm}20:08)(?{nine}?{pm}21:09)(?{ten}?{pm}22:10)(?{eleven}?{pm}23:11):$+{mins}:$+{secs}:$+{ms}

    Search mode: Regular expression

    (And I fully expect a “holy cow batman!” from @Meta-Chuh on that one!)

    (And yes, doing 12 differently from the others in the replace was intentional, as it is a little “out of place” in the conversion)

  • @Alan-Kilborn

    LOL - if I could I would upvote it 12 times. :-D

  • @Ekopalypse

    Sometimes things get upvoted too quickly for people to have tried it out to verify/duplicate results. This is somewhat bad as if something doesn’t work (and the thread dies right there) it looks to future readers like a good solution…

    BTW I think the “replace” is very readable with the named groups, but the “find” suffers…slightly…

  • @Alan-Kilborn

    :-D for me this looks like what we call - bohemian villages.
    But I can participate on that thread now - I’ve tested it, and it looks good to me :-)
    Let’s see what the OP thinks about it.

  • @Alan-Kilborn it works perfectly. Thank you so much!

  • 2nd solution is less confusing but both still produces the desired output. :D

  • @Alan-Kilborn

    holy cow batman! 😄👍

    Sometimes things get upvoted too quickly for people to have tried it out to verify/duplicate results.

    i guess sometimes your writing style is so worth an upvote, that people give you one, even if they have tested it’s content to fail.


  • @Meta-Chuh said:

    your writing style…worth an upvote…

    My writing style? Nah. I don’t have the flowery prose of a @PeterJones or the diplomatic panache of a @Meta-Chuh . [Basically I don’t wanna put that kind of effort in–to the typing part–obviously with the above regexes staring us in the face I’ll put a little time/effort into THAT aspect. Trying to provide some hopefully accurate help, maybe without the greatest english composition accompanying.]

  • Hi, @sophia-cruz, @alan-kilborn, @eko-palypse, @meta-chuh and All,

    Here is a variant of the Alan’s solution, which is less restrictive :

    • It just needs that the hour should be located after a non-word, instead of the beginning of line, due to the \b syntax

    • It does not care of the synbol between the different parts of the hour ( just changing the \. syntax by . ! )

    • It allows the milliseconds part to be absent ( .MMM ), in the hour, with the (?:.(\d{3}))? syntax

    • It allows the AM or PM part to come next to the digits, with \x20?

    • It does not care of the case , allowing the four syntaxes am, pm, AM and PM with the regex (?i:(AM)|PM)

    Note :
    In the remplacement regex, when group 17 exists ( AM ), I just rewrite the hour part ( \1 ), except when hour = 12, where the logic is reversed !

    So, assuming this sample text :

    12.00.47 AM am
    01 07 28 421 AM
    03:17:31:934am AM
            07:23:03.732 am
    11.57.59,003 am
    12.00.45 PM pm
    01 04 51 387 PM
    03:15:33:632pm PM
            07:33:55.548 pm
    11.59.11,247 pm

    With the regex S/R below :

    SEARCH :    \b(0(?:(1)|(2)|(3)|(4)|(5)|(6)|(7)|(8)|(9))|(10)|(11)|(12)).(\d\d).(\d\d)(?:.(\d{3}))?\x20?(?i:(AM)|PM)
                  │    │   │   │   │   │   │   │   │   │    │    │    │     │      │         │                │
                  1    2   3   4    5   6   7   8   9   10   11   12    13    14     15        16               17   <-- Groups
    REPLACE :   (?2(?17\1:13))(?3(?17\1:14))(?4(?17\1:15))(?5(?17\1:16))(?6(?17\1:17))(?7(?17\1:18))(?8(?17\1:19))(?9(?17\1:20))(?10(?17\1:21))(?11(?17\1:22))(?12(?17\1:23))(?13(?{17}00:\1)):$14:$15(?16\:$16)

    We would obtain :


    Best Regards,


  • Hi, All,

    When I woke up this morning, I immediately saw a simplification ( in length ! ) of the replacement regex ;-))

    So, my last version is :

    SEARCH \b(0(?:(1)|(2)|(3)|(4)|(5)|(6)|(7)|(8)|(9))|(10)|(11)|(12)).(\d\d).(\d\d)(?:.(\d{3}))?\x20?(?i:(AM)|PM)

    REPLACE (?13(?{17}00:\1):(?17\1:(?{2}13)(?{3}14)(?{4}15)(?{5}16)(?{6}17)(?{7}18)(?{8}19)(?{9}20)(?{10}21)(?{11}22)(?{12}23))):$14:$15(?16\:$16)



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