用switch语句编程的方法是什么？

#include<stdio.h>

int main()

{

int day,month,year,sum=0,leap;

printf("输入年月日如2019 7 12\n");

scanf("%d %d %d",&year,&month,&day);

switch(month)

{

case 1:sum=0;break;

case 2:sum=31;break;

case 3:sum=59;break;

case 4:sum=90;break;

case 5:sum=120;break;

case 6:sum=151;break;

case 7:sum=181;break;

case 8:sum=212;break;

case 9:sum=243;break;

case 10:sum=273;break;

case 11:sum=304;break;

case 12:sum=334;break;

default:printf("data error");break;

}

sum=sum+day;

if((year%400==0||(year%4==0&&year%100!=0))&&month>2)

sum++;

printf("这是这一年的第%d天。",sum);

return 0;

}

方法2

#include<stdio.h>

int day_of_year(int (*p)[13],int year,int month,int day)

{

int i,leap;

leap=(year%100!=0 && year%4 ==0||year%400 ==0);

for(i=1;i<month;i++)

day+=((p+leap)+i);

return day;

}

main()

{

static int day_tab[]

[13]={{0,31,28,31,30,31,30,31,31,30,31,30,31},

{0,31,29,31,30,31,30,31,31,30,31,30,31}};

int a,b,c;

scanf("%d %d %d",&a,&b,&c);

printf("%d\n",day_of_year(day_tab,a,b,c));

}