c# - String format to convert datetime causes an error -

i try convert persiandate standard date.so persian date has these formats (it means user can enter these formats :

1392/1/1 1392/01/01 1392/01/1 1392/1/01 

so write function convert persian date standard date :

 public datetime convertpeersiantoenglish(string persiandate)         {             string[] formats = { "yyyy/mm/dd" };             datetime d1 = datetime.parseexact(persiandate, formats,                                               cultureinfo.currentculture, datetimestyles.none);             persiancalendar persian_date = new persiancalendar();             datetime dt = persian_date.todatetime(d1.year, d1.month, d1.day, 0, 0, 0, 0, 0);             return dt;         } 

but these function can handle formats 1392/01/01 , of users enter other formats got error:

string not recognized valid datetime 

best regards

you're specifying mm , dd in format, require 2 digits. specify "yyyy/m/d" format - should handle both 1 , 2-digit day/month values. (you can specify multiple formats instead, in case don't need to. might want consider doing clear, m , d both handle 2 digit values leading 0 no problems.

note if you're specifying single format, don't need put in array. can use:

string format = "yyyy/m/d"; datetime d1 = datetime.parseexact(persiandate, format,                                   cultureinfo.currentculture,                                   datetimestyles.none); 

however:

• i suspect want specify invariant culture, given don't want this value affected culture
• your current approach of converting date persian calendar not work.

currently you're implicitly validating date given in gregorian calendar, you're treating persian date. example, 1392/02/30 valid persian date, not valid gregorian date.

instead, should use culture uses persian calendar, , specify that culture in datetime.parseexact call. don't need else afterwards.

you might alternatively want consider using noda time library - version 1.3 includes persian calendar should released in next day or two.

sample code using noda time:

var persian = calendarsystem.getpersiancalendar(); // pattern takes calendar system default value var sampledate = new localdate(1392, 1, 1, persian); var pattern = localdatepattern.createwithinvariantculture("yyyy/m/d")                               .withtemplatevalue(sampledate); var date = pattern.parse("1392/02/30").value; console.writeline(localdatepattern.isopattern.format(date));