CultureInfo on DateTime.ParseExact?

Question

I don't understand Why there is an overload with IFormatProvider in DateTime.ParseExact ?

If I'm defining exactly how it should be parsed ( spaces , separators etc) , then theres should be no problem :

All these 3 examples show the same result:

example 1

CultureInfo provider =CultureInfo.CreateSpecificCulture("en-US");
var t=  DateTime.ParseExact("13-2-2013", "d-M-yyyy", provider, DateTimeStyles.None);  
Console.WriteLine (t); //13/02/2013 00:00:00

example 2

  CultureInfo provider =CultureInfo.CreateSpecificCulture("en-US");
  var t=    DateTime.ParseExact("13/2/2013", "d/M/yyyy", provider, DateTimeStyles.None);  
  Console.WriteLine (t); //13/02/2013 00:00:00

example 3

 CultureInfo provider =CultureInfo.CreateSpecificCulture("en-US");
var t=  DateTime.ParseExact("13@@@2@@@2013", "d@@@M@@@yyyy", provider, DateTimeStyles.None);  
 Console.WriteLine (t); //13/02/2013 00:00:00

So why do i need to provide provider If I'm explicitly defining the structure ?

Answer 1

There are still format specifiers that are culture dependant, like the time separator (:) and the date separator (/). Those doesn't match a specific character, but the separator specified in the culture.

Answer 2

Because:

1. The specified format can include localized names of weekdays and months.
2. The characters : and / in the format string do not represent literal characters but rather the separator as specified by the format provider (see the bottom of the table here).