This way
protected void Page_Load(object sender, EventArgs e)
{
DateTime dt = new DateTime(1987, 7, 5);
string formattedDate = string.Format(dt.ToString("dd{0} MMMM yyyy"), GetSuffix(dt.Day.ToString()));
}
private string GetSuffix(string day)
{
string suffix = "th";
if (int.Parse(day) < 11 || int.Parse(day) > 20)
{
day = day.ToCharArray()[day.ToCharArray().Length - 1].ToString();
switch (day)
{
case "1":
suffix = "st";
break;
case "2":
suffix = "nd";
break;
case "3":
suffix = "rd";
break;
}
}
return suffix;
}