%02d

强悍的%02d，解决输出问题，节约代码，事半功倍

printf("%d-%02d-%02d %s\n",years,months,days,p[week]);
char *p[7]={"Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday"};
%02d好强啊，省了好多代码。宽度为2，不足左补0.我以前从来不知道！