try the code inside method. You can test it in console application
class Program
{
static void Main(string[] args)
{
DateTime DOB = Convert.ToDateTime("1988-08-02");
DateTime now = DateTime.Today;
int age = now.Year - DOB.Year;
if (DOB > now.AddYears(-age))
age--;
int month = now.Month - DOB.Month;
int datediff = 0;
int days = now.Day - DOB.Day;
while (days < 0)
{
datediff += 1;
days += 1;
}
string str = (31 - datediff) + "/" + month + "/" + age;
Console.WriteLine(str);
Console.ReadLine();
}
}