This question has been asked many times, it should be in FAQ1.
String s = "123";
int i = System.Convert.ToInt32(s);2.
String s = "123";
int i= System.Int32.Parse(s);
String s = "123";
int i = System.Convert.ToInt32(s);2.
String s = "123";
int i= System.Int32.Parse(s);
int request_number=(Int32.Parse(request_num));