第十九天的问题
1. swich语句的灵活运用
switch(month){
case 1:
case 3:
case 7:
case 5:
case 8:
case 10:
case 12:day=31;System.out.println("天数:"+day);break;
case 4:
case 6:
case 9:
case 11:day=30;System.out.println("天数:"+day);break;
case 2:day=29;System.out.println("天数:"+day);break;
2.
System.err.printf与System.out.printf使用并无大差异;