Convert a specific type of sting in Date Time

I would parse this as a DateTimeOffset instead of a DateTime - after all, that's the data you've been given. Assuming it's always specified using GMT+... you can use a format string of "ddd MMM d yyyy HH:mm:ss 'GMT'zzz". In particular, note:

• MMM is abbreviated month name, not mmm
• 'GMT' will always match the letters 'GMT'
• zzz is a UTC offset including minutes. It would be formatted with a colon, but apparently it's permissive enough without the colon being specified.

Sample code:

using System;
using System.Globalization;

class Test
{
    static void Main()
    {
        var dto = DateTimeOffset.ParseExact
            ("Sun Feb 23 2014 00:00:00 GMT+0550",
             "ddd MMM d yyyy HH:mm:ss 'GMT'zzz",
             CultureInfo.InvariantCulture);
        Console.WriteLine(dto); // 23/02/2014 00:00:00 +05:50
    }
}