The UDF should return a number to the cell, which can be formatted as
a date to suit your requirements. The number is an integer measuring
the number of elapsed days, with 1st Jan 1900 = Day 1. Excel assumes
(incorrectly) that 1900 was a leap year, so you need to take this into
account. The serial value for today's date (17th Jan 2008) is 39464.

Hope this helps.

Pete

On Jan 17, 11:31*pm, ep wrote:
Hi all,

I have a c# udf accessed as an automation add-in that needs to return dates
to Excel. I know I can't manipulate the cell's NumberFormat from within the
UDF, but is there a way to return a value that will be formatted in Excel as
a date? It seems any string value I return will default to general. Let me
know if any other info would help.

thanks

Dates are just integers to Excel, but the cell can be formatted to
display them in different ways, so that if you apply a date format to
the cell, then Excel will interpret the number according to the rules
I outlined earlier and display it in the chosen manner (i.e dd/mm/yy,
or mm/dd/yyyy, or mmm-dd etc. Consequently, the cell which contains
=your_udf( ... ) should also be formatted as a date in the appropriate
style.

Hope this helps.

Pete

On Jan 18, 12:25*am, ep wrote:
Hey Pete,

Thanks for the quick reply. If my udf just returns an int, won't Excel just
auto format it as a number? Is it even possible to return a value that Excel
will recognize and format as a date?

ep



"Pete_UK" wrote:
The UDF should return a number to the cell, which can be formatted as
a date to suit your requirements. The number is an integer measuring
the number of elapsed days, with 1st Jan 1900 = Day 1. Excel assumes
(incorrectly) that 1900 was a leap year, so you need to take this into
account. The serial value for today's date (17th Jan 2008) is 39464.

Hope this helps.

Pete

On Jan 17, 11:31 pm, ep wrote:
Hi all,

I have a c# udf accessed as an automation add-in that needs to return dates
to Excel. I know I can't manipulate the cell's NumberFormat from within the
UDF, but is there a way to return a value that will be formatted in Excel as
a date? It seems any string value I return will default to general. Let me
know if any other info would help.

thanks- Hide quoted text -

- Show quoted text -