c# hex函数
int i = 20100011;
string str = Convert.ToString(i, 16);
or
int i = 20100011;
string str = i.ToString("x16");
or
int i = 20100011;
string str = string.Format("0x{0:x16}", i);
int i = 20100011;
string str = Convert.ToString(i, 16);
or
int i = 20100011;
string str = i.ToString("x16");
or
int i = 20100011;
string str = string.Format("0x{0:x16}", i);