DateTime.TryParseExact does not return correct response

Question

Why would

 DateTime.TryParseExact("08/10/2013", "dd/MM/yyyy", null, DateTimeStyles.None, out dateValue)  

return false?

Answer 1

Use CultureInfo.InvariantCulture instead of null.

It tells the compiler that the format is culture-independent.

DateTime.TryParseExact("08/10/2013", 
                       "dd/MM/yyyy", 
                       CultureInfo.InvariantCulture, 
                       DateTimeStyles.None, 
                       out dateValue);`

If you use null, it is inferred as CultureInfo.CurrentCulture(msdn: "If provider is null, the CultureInfo object that corresponds to the current culture is used"). Also, since it's not that clear, the problem is that / is replaced by the provided culture's date-separator. It has a special meaning. http://msdn.microsoft.com/en-us/library/8kb3ddd4.aspx#dateSeparator

Here is a running example

Answer 2

Because you passed null for the IFormatProvider parameter. Try passing CultureInfo.InvariantCulture instead

EDIT As others mentioned, the actual reason is that / in the string to parse is itself translated using the rules provided by IFormatProvider. When you pass null the default value of CultureInfo.CurrentCulture is used.