How can I format a nullable DateTime with ToString()?

Question

How can I convert the nullable DateTime dt2 to a formatted string?

DateTime dt = DateTime.Now;
Console.WriteLine(dt.ToString(\"yyyy-MM-dd hh         


        

Answer 1

Here is a more generic approach. This will allow you to string format any nullable value type. I have included the second method to allow overriding the default string value instead of using the default value for the value type.

public static class ExtensionMethods
{
    public static string ToString<T>(this Nullable<T> nullable, string format) where T : struct
    {
        return String.Format("{0:" + format + "}", nullable.GetValueOrDefault());
    }

    public static string ToString<T>(this Nullable<T> nullable, string format, string defaultValue) where T : struct
    {
        if (nullable.HasValue) {
            return String.Format("{0:" + format + "}", nullable.Value);
        }

        return defaultValue;
    }
}

Answer 2

I like this option:

Console.WriteLine(dt2?.ToString("yyyy-MM-dd hh:mm:ss") ?? "n/a");