int i;scanf("%d",&i);select(i){case 0:i=3;case 1:i=4;case2:i=5;.....}与相同if...else语句即if (i==0){i=3;}else if(i==1){i=4;}else if(i==2){i=5;}if()select()条件相同两种相同同理条件相同则相同
