Paradox Date field to human readable format

[mphanke]

Hi,

can somebody tell me how to convert the date from a Paradox .DB to human
readable format?

I need to write a tool to convert the 4 Bytes representing the date to a
human readable format.

Thanks for your help,

Martin

 

[cody]

Use the DateTime constructor which takes a long (Int64) as parameter.
Iam not sure wheather the date is the higher or the lower 32 bits but you
can try it.

 

[Nicholas Paldino [.NET/C# MVP]]

Martin,

Are you using a Data Provider for the DB? If so, then the provider
should be responsible for changing it into a DateTime (assuming the column
is analagous to it).

If not, what are you using to get at the database?

 

[mphanke]

Hi,

since the application is to be installed on very old computers, I'm
bound to not using .NET . I'm reading the header and then parsing the file.

They are using some freaky representation of days since 1/1/1 (some type
of Julian date, but not really!) the dates I have are 1/1/100 which
corresponds to 36.160 and 5/4/1996 which is 728.783.

I just don't get how they are coding this stuff!?!?

Martin

 

[cpnet]

See:

http://www.thedbcommunity.com/code/date1.htm
and
http://www.thedbcommunity.com/code/date2.htm

 

[mphanke]

Hi,

thanks to everybody for the support. I figured out how to do this stuff.
It's a bit tricky but this snippet should do the conversion:

(- {BTW I know it is ugly coding =;-P}
This code is provided as is and comes with no guaranty what so ever!
Feel free to avoid the pain I had by using this snippet.
-)

Thanks,

Martin

int isLeap(int year)
{
return ((year % 4) == 0 && ((year % 100) != 0 || (year % 400)==0));
}

void ConvertDate(long days, int &day, int &month, int &year)
{
long _days;
int yearlengths[] = {365,366};
int length[2][12];

length[1][0] = length[0][0] = 31;
length[0][1] = 28;
length[1][1] = 29;
length[1][2] = length[0][2] = 31;
length[1][3] = length[0][3] = 30;
length[1][4] = length[0][4] = 31;
length[1][5] = length[0][5] = 30;
length[1][6] = length[0][6] = 31;
length[1][7] = length[0][7] = 31;
length[1][8] = length[0][8] = 30;
length[1][9] = length[0][9] = 31;
length[1][10] = length[0][10] = 30;
length[1][11] = length[0][11] = 31;

_days = days & 0x7fffffff ;
_days--;
year = 1;

int *len;
int leap = 0;

while(_days<0 || _days >= yearlengths[leap = isLeap(year)])
{
int nyear = year + _days/365;

if(_days < 0)
{
nyear--;
}

_days -= (nyear - year)*365 + ((nyear-1)/4 - (nyear-1)/100 +
(nyear-1)/400) -
((year-1)/4 - (year-1)/100 + (year-1)/400);
year = nyear;
}

len = length[leap];

for(month = 0; _days >= len[month]; month++)
{
_days -= len[month];
}

month++;

_days++;

day = _days;
}