Decoding the timestamp in class libararies and forms
I was asked
Is there a way to translate the timestamp in a VCX to a human readable format?
Visual Foxpro puts a timestamp on many records in the table that represents a form or class library. Historically this field was used to match records across supported platforms: DOS, Mac, Unix, Windows.
The VFP reserved variable “_screen” is an object reference to the Form instance that represents the VFP desktop. Because it’s a form instance, you can save it as a class using the SaveAsClass method. This will cause a timestamp record to be created that we can use to run the sample code. The sample code delays 3 seconds, creates a subclass of the form, adds a button, then shows the timestamps of the items in the class library.
The timestamp is in a standard format.
ERASE t.vcx
_screen.AddObject("btn","commandbutton") && add a button to the desktop
_screen.SaveAsClass("t.vcx","myform") && create class myform in a target file t.vcx
INKEY(3) && delay 3 seconds
MODIFY CLASS xx OF t.vcx as myform FROM t.vcx nowait && create a subclass of myform in the same file
ASELOBJ(aArray,1) && get an object reference to the class in the designer
aArray[1].addobject("btn2","commandbutton") && and btn2 to the class
aArray[1].btn2.top=200 && move it down so it doesn't hide btn
KEYBOARD "Y" && a "y" in the "Do you want to save changes")
RELEASE WINDOWS "Class designer" && close the designer
USE t.vcx && open the table
SCAN FOR timestamp!=0 && look for timestamps
?timestamp,DecodeTimeStamp(timestamp),objname+" "+class
ENDSCAN
PROCEDURE DecodeTimeStamp(nTimestamp as Number) as Datetime && see https://msdn.microsoft.com/library/default.asp?url=/library/en-us/sysinfo/base/filetimetodosdatetime.asp
nDate=BITRSHIFT(nTimestamp,16)
nTime=BITAND(nTimestamp,2^16-1)
nYear=BITAND(BITRSHIFT(nDate,9),2^8-1)+1980
nMonth=BITAND(BITRSHIFT(nDate,5),2^4-1)
nDay=BITAND(nDate,2^5-1)
nHr=BITAND(BITRSHIFT(nTime,11),2^5-1)
nMin=BITAND(BITRSHIFT(nTime,5),2^6-1)
nSec=BITAND(nTime,2^5-1)
RETURN DATETIME(nYear,nMonth,nDay,nHr,nMin,nSec)
RETURN
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