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.NET Forum / Languages / Managed C++ / January 2007Display a time span in days
I have a time saved in a time_t variable. I'd like to be able to display the number of days since then but can't find anything built-in that will help. Failing that I'd like to display the date (only the date) that corresponds to the saved time_t variable. Thanks for any help >I have a time saved in a time_t variable. > > I'd like to be able to display the number of days since then but can't find > anything built-in that will help. I believe dividing the number by (60*60*24) might give you the number of days (depends on what exactly you have in that variable). Be careful about how the result is rounded, though. > Failing that I'd like to display the date (only the date) that corresponds to > the saved time_t variable.  Signature"It is easy in the world to live after the world's opinion; it easy in solitude to live after our own; but the great man is he who in the midst of the crowd keeps with perfect sweetness the independence of solitude." Ralph Waldo Emerson, Self-reliance 1841 http://pinpoint.wordpress.com/ Thanks Actually I thought of that after I posted. That question was an after thought - without too much thought. The main reason for posting is that I wanted to display a saved date, without the time, and it seems there must be an easier way that what I was doing. Thanks a lot >>I have a time saved in a time_t variable. >> [quoted text clipped - 7 lines] >> Failing that I'd like to display the date (only the date) that >> corresponds to the saved time_t variable. > Thanks > [quoted text clipped - 4 lines] > without the time, and it seems there must be an easier way that what I was > doing. First gmtime or localtime to get a struct tm, then strftime with a format string of your choice. > Thanks a lot > [quoted text clipped - 9 lines] >>> Failing that I'd like to display the date (only the date) that >>> corresponds to the saved time_t variable. I'll look at that. I did tried tm once but if I remember I got 2 for example rather than March. Maybe strftime was what I missed. In your prior post you cautioned about rounding. Thanks for that. I got 0 when I expected 1 until I remember your caution. thanks >> Thanks >> [quoted text clipped - 21 lines] >>>> Failing that I'd like to display the date (only the date) that >>>> corresponds to the saved time_t variable. > I'll look at that. I did tried tm once but if I remember I got 2 for > example rather than March. > Maybe strftime was what I missed. > > In your prior post you cautioned about rounding. Thanks for that. I got 0 > when I expected 1 until I remember your caution. Wasn't my post actually, but... Define what you mean by "number of days since then". If the saved time is 11:59 PM on Feb 1, and current system time is 12:03 AM on Feb 2, the delay is only 4 minutes, but midnight passed... so do you count that as a day? Rounding won't really help you there. If you mean calendar days, then you may want to convert your time_t to a tm using localtime, zero the hour/minute/second fields, use mkgmtime to go back to time_t, then difftime and divide by (24*60*60). In that way you will count days elapsed since the beginning of the day in which the saved time occurred. > thanks > [quoted text clipped - 23 lines] >>>>> Failing that I'd like to display the date (only the date) that >>>>> corresponds to the saved time_t variable. > If you mean calendar days, then you may want to convert your time_t > to a tm using localtime, zero the hour/minute/second fields, use > mkgmtime to go back to time_t, then difftime and divide by > (24*60*60). In that way you will count days elapsed since the > beginning of the day in which the saved time occurred. or just do the division first, then the subtraction: int num_days = (end_time_t / 86400) - (start_time_t/86400); Will always give the difference in day number between two time_t values. If you want the "rollover" from one day to the next to be at a time other than midnight (e.g. to counts days in a different timezone than the one represented in your time_t), then just subtract the appropriate number of hours*3600 from each time_t before dividing. -cd Thanks for all the insight. I'm showing the days since and also the prior date. I got two extra characters displayed so I added the last line shown below. Can you tell me what is going on? Thanks again struct tm pasttime; localtime_s( &pasttime, &OldTime ); strftime( szTmpStr, 100, "%A %B %d, %Y\n", &pasttime ); szTmpStr[lstrlen(szTmpStr)-1] = 0; > Thanks for all the insight. > > I'm showing the days since and also the prior date. > > I got two extra characters displayed so I added the last line shown below. That extra line removes the newline character you have in the format string. Perhaps it's also going through newline translation and becoming a CR/LF pair. Try just removing the "\n" from the format string. > Can you tell me what is going on? > [quoted text clipped - 7 lines] > > szTmpStr[lstrlen(szTmpStr)-1] = 0; ouch! thanks >> Thanks for all the insight. >> [quoted text clipped - 20 lines] >> >> szTmpStr[lstrlen(szTmpStr)-1] = 0;
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