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Geir Baardsen
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 Posted: Sun Jan 09, 2005 8:21 am Post subject: Time calculation |
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Hi!
My app is a personal scheduler. I use a stringgrid with 10 columns:
MonIN MonOUT TueIN TueOUT WedIN WedOUT ThuIN ThuOUT FriIN FriOUT
when I click a cell, the time will be set in the format of:
FormatDateTime('HH:MM',time);
So now I want to calculate the total in time between MonIN and FriOUT.
I should surely convert it or cast it to a double, not so?
var
Monsum:double;
begin
for i := 0 to StrToFloat(grSched.Cells[1,Monsum]);
Anybody that have an example of how to work with time?
Me.Name
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Tom de Neef
Guest
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| Posted: Sun Jan 09, 2005 10:08 am Post subject: Re: Time calculation |
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"Geir Baardsen" <geir_baardsen (AT) hotmail (DOT) com> schreef in bericht
news:35f9d8b7.0501090021.7e56782c (AT) posting (DOT) google.com...
| Quote: | Hi!
My app is a personal scheduler. I use a stringgrid with 10 columns:
MonIN MonOUT TueIN TueOUT WedIN WedOUT ThuIN ThuOUT FriIN FriOUT
when I click a cell, the time will be set in the format of:
FormatDateTime('HH:MM',time);
So now I want to calculate the total in time between MonIN and FriOUT.
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Check help: TdateTime
"The integral part of a TDateTime value is the number of days that have
passed since 12/30/1899. The fractional part of a TDateTime value is
fraction of a 24 hour day that has elapsed."
So,
difference:=FriOUT-MonIN;
is the elapsed time between these two.
trunc(difference) is then the number of days
trunc(difference*24) the number of full hours elapsed, etc.
Tom
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Jamie
Guest
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| Posted: Sun Jan 09, 2005 7:11 pm Post subject: Re: Time calculation |
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Geir Baardsen wrote:
| Quote: | Hi!
My app is a personal scheduler. I use a stringgrid with 10 columns:
MonIN MonOUT TueIN TueOUT WedIN WedOUT ThuIN ThuOUT FriIN FriOUT
when I click a cell, the time will be set in the format of:
FormatDateTime('HH:MM',time);
So now I want to calculate the total in time between MonIN and FriOUT.
I should surely convert it or cast it to a double, not so?
var
Monsum:double;
begin
for i := 0 to StrToFloat(grSched.Cells[1,Monsum]);
Anybody that have an example of how to work with time?
Me.Name
the TDateTime type is a double, the fraction is the |
fraction of the day.
in other words, 0.5 would be 12:00 and 0.0 would be
be 24:00 (midnight) etc..
i guess one could take a DataTime's fraction and turn that into
an integer by taking the scale you want for the day and * the Fraction.
for example, the N = SecondsOfTheDay = (DateTime-Trunc(DateTime))*86400;
ect.
from there i think you can work that out.
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Dr John Stockton
Guest
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| Posted: Sun Jan 09, 2005 8:17 pm Post subject: Re: Time calculation |
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JRS: In article <35f9d8b7.0501090021.7e56782c (AT) posting (DOT) google.com>,
dated Sun, 9 Jan 2005 00:21:25, seen in news:comp.lang.pascal.delphi.mis
c, Geir Baardsen <geir_baardsen (AT) hotmail (DOT) com> posted :
| Quote: | MonIN MonOUT TueIN TueOUT WedIN WedOUT ThuIN ThuOUT FriIN FriOUT
when I click a cell, the time will be set in the format of:
FormatDateTime('HH:MM',time);
So now I want to calculate the total in time between MonIN and FriOUT.
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There is no need to bother with TDateTime. You have days 1..5 of the
ISO 8061:2004 week, you have 24 hours per day and 60 minutes per hour.
Just take each HH:MM string, copy HH & MM, use Val or maybe StrToInt,
then Mins := HH*60+MM, etc.
With TDateTime, since the data is stored as a float binary of days, and
the number of H M S in a day is not a power of 2, there must be some
risk of rounding error; with integer arithmetic, all is exact.
--
© John Stockton, Surrey, UK. ?@merlyn.demon.co.uk Turnpike v4.00 MIME. ©
Web <URL:http://www.merlyn.demon.co.uk/> - w. FAQish topics, links, acronyms
PAS EXE etc : <URL:http://www.merlyn.demon.co.uk/programs/> - see 00index.htm
Dates - miscdate.htm moredate.htm js-dates.htm pas-time.htm critdate.htm etc.
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