1 #define m(a,b) a::b 2 =m(123, 3 456) 4 ------ 5 =m 6 (123, 456) 7 ------ 8 =m( 9 123, 456) 10 ------ 11 =m( 12 123, 13 456 14 ) 15 ------ 16 =m(123, 17 18 456) 19 ------ 20 =m(123, 21 456) 22