c++ - incorrect value in coledatetime -


i'm fighting few days coledatetime in mfc. have ctime correct values. correct years, days, months, hours, minutes , seconds. tried few ways convert ctime coledatetime:

-1.i put ctime data constructor of coledatetime 

coledatetime(int nyear,int nmonth,int nday, int nhour, int nmin,int nsec );

-2. formatted ctime time.format("%m/%d/%y %h:%m:%s");

and passed parsedatetime of coledatetime.

-3. tried use setdatetime of coledatetime

after i'm getting incorrect values of minutes 1-2 min. more or less. have never seen before , couldn't find nothing in internet.everybody says abot loss precision second, not minute. please advice me! thank you

i think problem coledatetime internally uses float storage, , value represents number of days since 30 december 1899.

as number of days gets larger, precision of smaller fields (like minutes) decreases. example, float can accurately store values 1000000 , 0.0000001, can't store 1000000.0000001. doesn't have enough bits of precision.

this limitation hinted @ in msdn documentation:

this type used represent date-only or time-only values. convention, date 0 (30 december 1899) used time-only values. similarly, time 0:00 (midnight) used date-only values.

so basically, if want precise time, set date 30 december 1899.

it seems microsoft have designed class store "days" portion integer, hey, easy.


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