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DateAdd equivalent?

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  • N nm_114

    DavidCrow wrote:

    If you are using MFC, see the COleDateTime class.

    Nope, pure Win32 :(

    D Offline
    D Offline
    David Crow
    wrote on last edited by
    #5

    Ok. How are you obtaining the date value you want to manipulate?


    "Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

    "Judge not by the eye but by the heart." - Native American Proverb

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    • D David Crow

      Ok. How are you obtaining the date value you want to manipulate?


      "Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

      "Judge not by the eye but by the heart." - Native American Proverb

      N Offline
      N Offline
      nm_114
      wrote on last edited by
      #6

      GetSystemTime() (then converting it to local time).

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      • N nm_114

        GetSystemTime() (then converting it to local time).

        D Offline
        D Offline
        David Crow
        wrote on last edited by
        #7

        So do you have a SYSTEMTIME or a FILETIME object at this point?


        "Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

        "Judge not by the eye but by the heart." - Native American Proverb

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        • D David Crow

          So do you have a SYSTEMTIME or a FILETIME object at this point?


          "Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

          "Judge not by the eye but by the heart." - Native American Proverb

          N Offline
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          nm_114
          wrote on last edited by
          #8

          SYSTEMTIME.

          SYSTEMTIME stDateIWantToAddDaysOrMonthsTo;
          FILETIME ft, ftLocal;
          GetSystemTimeAsFileTime(&ft);
          FileTimeToLocalFileTime(&ft, &ftLocal);
          FileTimeToSystemTime(&ftLocal, &stDateIWantToAddDaysOrMonthsTo);

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          • N nm_114

            SYSTEMTIME.

            SYSTEMTIME stDateIWantToAddDaysOrMonthsTo;
            FILETIME ft, ftLocal;
            GetSystemTimeAsFileTime(&ft);
            FileTimeToLocalFileTime(&ft, &ftLocal);
            FileTimeToSystemTime(&ftLocal, &stDateIWantToAddDaysOrMonthsTo);

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            D Offline
            David Crow
            wrote on last edited by
            #9

            Ok, so what problem(s) are you having with "add or subtract any amount of hours, days, months etc. to a date?"


            "Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

            "Judge not by the eye but by the heart." - Native American Proverb

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            • D David Crow

              Ok, so what problem(s) are you having with "add or subtract any amount of hours, days, months etc. to a date?"


              "Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

              "Judge not by the eye but by the heart." - Native American Proverb

              N Offline
              N Offline
              nm_114
              wrote on last edited by
              #10

              I don't know of any function that does this. I was looking for something like VBScript's DateAdd where I could do something like DateAdd(Month, 24, &stMyDate) and it would add 24 months to the date (2 years), taking into account leap years etc..

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              • N nm_114

                I don't know of any function that does this. I was looking for something like VBScript's DateAdd where I could do something like DateAdd(Month, 24, &stMyDate) and it would add 24 months to the date (2 years), taking into account leap years etc..

                D Offline
                D Offline
                David Crow
                wrote on last edited by
                #11

                nm_114 wrote:

                I don't know of any function that does this.

                Why would you need a function, when one statement will work:

                stDateIWantToAddDaysOrMonthsTo.wYear += 2;

                You could roll your own function to this I suppose. Take a stroll through the other date/time functions to see what is available to you.


                "Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

                "Judge not by the eye but by the heart." - Native American Proverb

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                • D David Crow

                  nm_114 wrote:

                  I don't know of any function that does this.

                  Why would you need a function, when one statement will work:

                  stDateIWantToAddDaysOrMonthsTo.wYear += 2;

                  You could roll your own function to this I suppose. Take a stroll through the other date/time functions to see what is available to you.


                  "Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

                  "Judge not by the eye but by the heart." - Native American Proverb

                  N Offline
                  N Offline
                  nm_114
                  wrote on last edited by
                  #12

                  DavidCrow wrote:

                  Why would you need a function, when one statement will work:

                  It was a bad example I guess. It needs to be arbitrary. Like DateAdd(Month, 309, mydate), DateAdd(Day, -909, mydate) etc. I'm not sure if I'm explaining it right.

                  DavidCrow wrote:

                  Take a stroll through the other date/time functions to see what is available to you.

                  I did. I didn't see anything like DateAdd.

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                  • N nm_114

                    DavidCrow wrote:

                    Why would you need a function, when one statement will work:

                    It was a bad example I guess. It needs to be arbitrary. Like DateAdd(Month, 309, mydate), DateAdd(Day, -909, mydate) etc. I'm not sure if I'm explaining it right.

                    DavidCrow wrote:

                    Take a stroll through the other date/time functions to see what is available to you.

                    I did. I didn't see anything like DateAdd.

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                    D Offline
                    David Crow
                    wrote on last edited by
                    #13

                    If you convert the SYSTEMTIME structure to a FILETIME structure, you can add/subtract such values.


                    "Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

                    "Judge not by the eye but by the heart." - Native American Proverb

                    N 1 Reply Last reply
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                    • D David Crow

                      If you convert the SYSTEMTIME structure to a FILETIME structure, you can add/subtract such values.


                      "Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

                      "Judge not by the eye but by the heart." - Native American Proverb

                      N Offline
                      N Offline
                      nm_114
                      wrote on last edited by
                      #14

                      :confused: How? I found an article at http://www.codeproject.com/datetime/winapi_datetime_ops.asp[^] but it doesn't work with months/years, and I have no idea if it works right with leap years etc.

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                      • N nm_114

                        :confused: How? I found an article at http://www.codeproject.com/datetime/winapi_datetime_ops.asp[^] but it doesn't work with months/years, and I have no idea if it works right with leap years etc.

                        D Offline
                        D Offline
                        David Crow
                        wrote on last edited by
                        #15

                        nm_114 wrote:

                        How?

                        By using SystemTimeToFileTime().

                        nm_114 wrote:

                        I found an article at http://www.codeproject.com/datetime/winapi\_datetime\_ops.asp\[^\]

                        That article is exactly what you need.

                        nm_114 wrote:

                        but it doesn't work with months/years

                        That's because a month does not have a constant value (i.e., 28, 29, 30, or 31 days) like the other items do.


                        "Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

                        "Judge not by the eye but by the heart." - Native American Proverb

                        N 1 Reply Last reply
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                        • D David Crow

                          nm_114 wrote:

                          How?

                          By using SystemTimeToFileTime().

                          nm_114 wrote:

                          I found an article at http://www.codeproject.com/datetime/winapi\_datetime\_ops.asp\[^\]

                          That article is exactly what you need.

                          nm_114 wrote:

                          but it doesn't work with months/years

                          That's because a month does not have a constant value (i.e., 28, 29, 30, or 31 days) like the other items do.


                          "Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

                          "Judge not by the eye but by the heart." - Native American Proverb

                          N Offline
                          N Offline
                          nm_114
                          wrote on last edited by
                          #16

                          DavidCrow wrote:

                          nm_114 wrote: How? By using SystemTimeToFileTime().

                          Well I knew that much! :-D I was asking how you do the adding/subtracting...

                          DavidCrow wrote:

                          That article is exactly what you need.

                          Well not really, as it doesn't handle months/years.

                          DavidCrow wrote:

                          That's because a month does not have a constant value (i.e., 28, 29, 30, or 31 days) like the other items do.

                          I knew that too! :-D But it's ok, I guess what I was looking for doesn't exist (a tested/bug-free exact replica of DateAdd() in C++). Oh well :sigh:. Thanks anyway.

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                          • N nm_114

                            DavidCrow wrote:

                            nm_114 wrote: How? By using SystemTimeToFileTime().

                            Well I knew that much! :-D I was asking how you do the adding/subtracting...

                            DavidCrow wrote:

                            That article is exactly what you need.

                            Well not really, as it doesn't handle months/years.

                            DavidCrow wrote:

                            That's because a month does not have a constant value (i.e., 28, 29, 30, or 31 days) like the other items do.

                            I knew that too! :-D But it's ok, I guess what I was looking for doesn't exist (a tested/bug-free exact replica of DateAdd() in C++). Oh well :sigh:. Thanks anyway.

                            D Offline
                            D Offline
                            David Crow
                            wrote on last edited by
                            #17

                            nm_114 wrote:

                            Well not really, as it doesn't handle months/years.

                            I already showed you how to add months to the SYSTEMTIME object. You would add years in the same fashion. What you have to account for when adding months is to make sure to increment years accordingly. For example, if it's September and you want to add four months, you would use:

                            wMonth = (wMonth + 4) % 12; // which would produce 0, for January

                            But you would then have to add one to the year.


                            "Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

                            "Judge not by the eye but by the heart." - Native American Proverb

                            N 1 Reply Last reply
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                            • D David Crow

                              nm_114 wrote:

                              Well not really, as it doesn't handle months/years.

                              I already showed you how to add months to the SYSTEMTIME object. You would add years in the same fashion. What you have to account for when adding months is to make sure to increment years accordingly. For example, if it's September and you want to add four months, you would use:

                              wMonth = (wMonth + 4) % 12; // which would produce 0, for January

                              But you would then have to add one to the year.


                              "Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

                              "Judge not by the eye but by the heart." - Native American Proverb

                              N Offline
                              N Offline
                              nm_114
                              wrote on last edited by
                              #18

                              Yep. I guess I was hesitant to write my own because I don't know how to account for leap years, but I guess it's not critical. I'll probably use that other article and write something similar to your example for months/years. Thanks.

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                              • N nm_114

                                Yep. I guess I was hesitant to write my own because I don't know how to account for leap years, but I guess it's not critical. I'll probably use that other article and write something similar to your example for months/years. Thanks.

                                D Offline
                                D Offline
                                David Crow
                                wrote on last edited by
                                #19

                                nm_114 wrote:

                                ...I don't know how to account for leap years...

                                Are you kidding? Leap year algorithms/functions are plentiful here at CP, or even Googling for them.


                                "Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

                                "Judge not by the eye but by the heart." - Native American Proverb

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