方法一、

int转IntPtr

int i = 12;
           IntPtr p = new IntPtr(i);

IntPtr转int

int myi = (int)p;
           MessageBox.Show(myi.ToString());

方法二、

int转IntPtr

int i = 12;
           IntPtr p =(IntPtr)i

IntPtr转int

int myi = (int)p;
           MessageBox.Show(myi.ToString());