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Gerad
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Joined: 10/01/2024
Location: Germany
Posts: 34

Posted: 02:16pm 12 Mar 2024

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Hello Everybody
How can I add days? For example
Today's date (03/12/2024) plus 7 days equals (03/19/2024)

Who can help or give tips on where I can find information about this problem?
Thanks in advance

Volhout
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Joined: 05/03/2018
Location: Netherlands
Posts: 3529

Posted: 03:23pm 12 Mar 2024

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Hi Gerad,

Look at the n=Epoch(DateTime$) function. You change the date/time to a large integer number (seconds since xx), add the 7 days (in seconds), and convert back using DateTime$(n).

Regards,

Volhout
Edited 2024-03-13 01:23 by Volhout

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matherp
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Joined: 11/12/2012
Location: United Kingdom
Posts: 8582

Posted: 03:23pm 12 Mar 2024

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Tip - look at the epoch function and the datetime$ function

Mixtel90

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Joined: 05/10/2019
Location: United Kingdom
Posts: 5727

Posted: 03:28pm 12 Mar 2024

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The best way is to set a base date. Then you convert your date to the number of days since the base date. The next step is to add (or subtract) a number of days to (or from) your number of days. Then you convert the base date + resulting number of days to a new date.

It sounds like a long way round, but basically you need two functions:

Given a date, return the number of days since base date.
and
Given a number of days, return a date since the base date.

Your base date can be anything earlier than the earliest date you will need.
Beware of leap years!

This is how we used to do it. There are better ways now.
Edited 2024-03-13 01:29 by Mixtel90

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Gerad
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Joined: 10/01/2024
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Posts: 34

Posted: 04:39pm 12 Mar 2024

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many thanks for your help

Gerad

cdeagle
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Joined: 22/06/2014
Location: United States
Posts: 261

Posted: 06:04pm 12 Mar 2024

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' demo_dates.bas

' demonstrate date conversions

' March 2, 2017

'''''''''''''''

print " "
print "program demo_dates - demonstrate date conversions"
print "================================================="

' request calendar date (month, day, year)

getdate(month1, day0, year1)

' request time (hours, minutes, seconds)

gettime(thr1, tmin1, tsec1)

' compute "complete" calendar day

day1 = day0 + thr1 / 24.0 + (tmin1 / 60.0) / 24.0 + (tsec1 / 3600.0) / 24.0

' compute corresponding Julian day

julian (month1, day1, year1, jday1)

' print results

print " "

print "convert calendar date and time to julian day"

print "--------------------------------------------"

print " "

print "calendar month = ", month1

print "calendar day = ", day0

print "calendar year = ", year1

print " "

print "time = ", str$(thr1) + " hr " + str$(tmin1) + " min " + str$(tsec1, 0, 4) + " sec"

print " "

print "jday = ", str$(jday1, 0, 9)

print " "

print "convert Julian day to Gregorian date and time"

print "---------------------------------------------"

print " "

print "jday = ", str$(jday1, 0, 9)

' compute calendar date

gdate (jday1, month2, day2, year2)

print " "

print "calendar month = ", month2

print "calendar day = ", int(day2)

print "calendar year = ", year2

print " "

thr0 = 24.0 * (day2 - int(day2))

thr2 = int(thr0)

tmin0 = 60.0 * (thr0 - thr2)

tmin2 = int(tmin1)

tsec2 = 60.0 * (tmin0 - tmin2)

print "time = ", str$(thr2) + " hr " + str$(tmin2) + " min " + str$(tsec2, 0, 4) + " sec"

print " "

print "number of days between two dates"

print "--------------------------------"

print " "

print "first date"

getdate(month3, day3, year3)

julian (month3, day3, year3, jday3)

print " "

print "second date"

getdate(month4, day4, year4)

julian (month4, day4, year4, jday4)

delta_days = jday4 - jday3

print " "

print "number of days between dates = ", delta_days

print " "

end

'''''''''''''''''''''''''''''''''''
'''''''''''''''''''''''''''''''''''

sub julian (month, day, year, jday)

' Gregorian date to julian day subroutine

' input

' month = calendar month
' day = calendar day
' year = calendar year (all four digits)

' output

' jday = julian day

' special notes

' (1) calendar year must include all digits

' (2) will report October 5, 1582 to October 14, 1582
' as invalid calendar dates and exit

'''''''''''''''''''''''''''''''''''''''''

y = year

m = month

b = 0.0

c = 0.0

if (m <= 2.0) then

y = y - 1.0

m = m + 12.0

end if

if (y < 0.0) then c = -0.75.0

if (year < 1582.0) then

' null

elseif (year > 1582.0) then

a = fix(y / 100.0)

b = 2.0 - a + fix(a / 4.0)

elseif (month < 10.0) then

' null

elseif (month > 10.0) then

a = fix(y / 100.0)

b = 2.0 - a + fix(a / 4.0)

elseif (day <= 4.0) then

' null

elseif (day > 14.0) then

a = fix(y / 100.0)

b = 2.0 - a + fix(a / 4.0)

else

print "this date does not exist!!"

exit

end if

jday = fix(365.25 * y + c) + fix(30.6001 * (m + 1.0)) + day + b + 1720994.5

end sub

''''''''''''''''''''''''''''''''''
''''''''''''''''''''''''''''''''''

sub gdate (jday, month, day, year)

' Julian day to Gregorian date subroutine

' input

' jday = julian day

' output

' month = calendar month
' day = calendar day
' year = calendar year

''''''''''''''''''''''''

z = fix(jday + 0.5)

f = jday + 0.5 - z

if (z < 2299161) then

a = z

else

alpha = fix((z - 1867216.25) / 36524.25)

a = z + 1.0 + alpha - fix(alpha / 4.0)

end if

b = a + 1524.0

c = fix((b - 122.1) / 365.25)

d = fix(365.25 * c)

e = fix((b - d) / 30.6001)

day = b - d - fix(30.6001 * e) + f

if (e < 13.5) then

month = e - 1.0

else

month = e - 13.0

end if

if (month > 2.5) then

year = c - 4716.0

else

year = c - 4715.0

end if

end sub

''''''''''''''''''''''''''''''
''''''''''''''''''''''''''''''

sub getdate (month, day, year)

' request calendar date subroutine

do
print " "
print "please input the calendar date"
print " "
print "(month [1 - 12], day [1 - 31], year [yyyy])"
print "< for example, october 21, 1986 is input as 10,21,1986 >"
print "< b.c. dates are negative, a.d. dates are positive >"
print "< the day of the month may also include a decimal part >"
print " "
input month, day, year

loop until (month >= 1 and month <= 12) and (day >= 1 and day <= 31)

end sub

'''''''''''''''''''''''''''''
'''''''''''''''''''''''''''''

sub gettime (thr, tmin, tsec)

' request time subroutine

do
print " "
print "please input the time"
print " "
print "(hours [0 - 24], minutes [0 - 60], seconds [0 - 60])"
print " "
input thr, tmin, tsec

loop until (thr >= 0.0 and thr <= 24.0 and tmin >= 0.0 and tmin <= 60.0 and tsec >= 0.0 and tsec <= 60.0)

end sub

barewires
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Joined: 13/04/2015
Location: United Kingdom
Posts: 25

Posted: 08:06pm 12 Mar 2024

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Decades ago I used to type in Sky and Telescope magazine BASIC code for astronomy.
https://skyandtelescope.org/astronomy-resources/basic-programs-from-sky-telescope/
Simply remove the line numbers in a .CSV file and fix the gosub, goto and labels etc.

> run
Enter your birthday (M,D,Y)? 4,2,1950
Enter desired age in days ? 27008
You will be 27008 days old on 3 12 2024

Verify with:
https://www.timeanddate.com/date/durationresult.html?d1=02&m1=04&y1=1950&d2=&m2=&y2=

Rem DAYSOLD.BAS
Input "Enter your birthday (M,D,Y)";M,D,Y
Rem Compute Julian Day Number
J=-Int(7*(Int((M+9)/12)+Y)/4)
S=Sgn(M-9)
A=Abs(M-9)
J1=Int(Y+S*Int(A/7))
J1=-Int((Int(J1/100)+1)*3/4)
J=J+Int(275*M/9)+D+J1
J=J+1721028+367*Y
G110: Input "Enter desired age in days ";A9
If A9=0 Then G280
Rem Compute calendar date from new JD number
J2=J+A9+1
A1=Int((J2/36524.25)-51.12264)
A=J2+1+A1-Int(A1/4)
B=A+1524
C=Int((B/365.25)-0.3343)
D=Int(365.25*C)
E=Int((B-D)/30.61)
D=B-D-Int(30.61*E)
M=E-1
Y=C-4716
If E>13.5 Then M=M-12
If M<2.5 Then Y=Y+1
Print "You will be "; A9; " days old on " ;M;D;Y
GoTo G110
G280: End
Rem ---------------------------
Rem APPEARED IN COMPUTERS IN
Rem ASTRONOMY, SKY & TELESCOPE,
Rem NOVEMBER 2001, PAGE 63
Rem ---------------------------

Edited 2024-03-13 07:07 by barewires

barewires
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Joined: 13/04/2015
Location: United Kingdom
Posts: 25

Posted: 09:37pm 12 Mar 2024

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https://skyandtelescope.org/wp-content/uploads/calendar.bas

Rem PERPETUAL GREGORIAN CALENDAR
Rem
Dim C$(42), D$(31), E(12)
For I=1 To 31: Read D$(I): Next I
For I=1 To 12: Read E(I): Next I
Data " 1"," 2"," 3"," 4"," 5"," 6"," 7"," 8"," 9"," 10"
Data " 11"," 12"," 13"," 14"," 15"," 16"," 17"," 18"," 19"," 20"
Data " 21"," 22"," 23"," 24"," 25"," 26"," 27"," 28"," 29"," 30"," 31"
Data 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
G28: Print : Input "MONTH, YEAR";M,Y: If Y<100 Then Y=Y+1900
Print : Print " SU MO TU WE TH FR SA": Print
J=367*Y-Int(7*(Y+Int((M+9)/12))/4)+Int(275*M/9)+1721031
K=0: If M<=2 Then K=-1
J=J-Int(3*(Int((Y+K)/100)+1)/4)
K=E(M): If M<>2 Then GoTo G48
W=Int(Y-100*Int(Y/100)): X=Int(Y-4*Int(Y/4)): Z=Int(Y-400*Int(Y/400))
If X<>0 Then GoTo G48
If W=0 And Z<>0 Then GoTo G48
K=29
G48: X=J-7*Int(J/7)
For I=1 To 42: C$(I)=" ": Next I
For I=1 To K: C$(I+X)=D$(I): Next I
For I=1 To 6: J=7*I
Print C$(J-6);C$(J-5);C$(J-4);C$(J-3);C$(J-2);C$(J-1);C$(J)
Next I
Print : Input "ANOTHER";A$: If A$="Y" Then G28
End
Rem ---------------------------------------------------------------
Rem APPEARED IN ASTRONOMICAL COMPUTING, SKY & TELESCOPE, JULY, 1985
Rem ---------------------------------------------------------------
[CODE/]

TassyJim

Guru

Joined: 07/08/2011
Location: Australia
Posts: 5905

Posted: 01:54am 13 Mar 2024

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In most versions of MMBasic you can keep it simple:

'
startDate$ = "02-04-1950"
startDate$ = startDate$+" 00:00:00"
DaysToAdd = 27008
EndDate$= DATETIME$(EPOCH(startDate$) + DaysToAdd*86400)
PRINT EndDate$

as suggested in the first two replies.

Jim
Edited 2024-03-13 11:55 by TassyJim

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homa

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Joined: 05/11/2021
Location: Germany
Posts: 241

Posted: 08:59pm 13 Mar 2024

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great Jim

Matthias

Gerad
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Joined: 10/01/2024
Location: Germany
Posts: 34

Posted: 09:18am 14 Mar 2024

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Hello Jim,
thank you very much for the program example. It solved my little problem immediately.
Greetings to Australia.
I would also like to thank everyone else for their help

Gerad

CaptainBoing

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Joined: 07/09/2016
Location: United Kingdom
Posts: 1985

Posted: 10:50am 14 Mar 2024

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always check the libraries

https://tbsassist.com/wiki/doku.php?id=mmbasic:dateadd_function_vb_work_a_like

disco4now

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Joined: 18/12/2014
Location: Australia
Posts: 844

Posted: 11:51am 14 Mar 2024

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Hi Andrew,
Good to see you making a couple of posts.
The original fruitoftheshed.com domain was successfully transfer to the new site and registered for the next six years so will live on with its original URL.

https://fruitoftheshed.com/wiki/doku.php?id=mmbasic:dateadd_function_vb_work_a_like

Regards
Gerry

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