用C语言实现一个日历显示

#include <stdio.h>
#include <stdlib.h>
#define SIGN_WEEK 6
#define SIGN_YEAR 2000
int month_day[14]={31,31,0,31,30,31,30,31,31,30,31,30,31,31};
char month_name[12][10]={"January","February","March","Apirl","May","June","July","August","September","October","November","December"};
void calendar(int week,int year) //显示日历
{
int i,j,n,m,num0=0,num1=31,nweek0=week,nweek1;
if(year%4==0)
{
if(year%100!=0) month_day[2]=29;
else
{
if(year%400==0) month_day[2]=29;
else month_day[2]=28;
}
}
else month_day[2]=28;
system("CLS");
printf("The calendar of the year %d\n\n",year);
for(m=0;m!=12;m+=2)
{
if(m-1<0)
{
nweek0=week;
nweek1=(week+num1%7)>7?(week+num1%7)-7:(week+num1%7);
}
else
{
num0=num0+month_day[m-1]+month_day[m];
nweek0=(week+num0%7)>7?(week+num0%7)-7:(week+num0%7);
num1=num1+month_day[m]+month_day[m+1];
nweek1=(week+num1%7)>7?(week+num1%7)-7:(week+num1%7);
}
printf("%-10s %2d %-10s %2d\n=========================== ===========================\nSun Mon Tue Wed Thu Fri Sat Sun Mon Tue Wed Thu Fri Sat\n",month_name[m],m+1,month_name[m+1],m+2);
for(i=nweek0,j=nweek1,n=0;j!=nweek1-6*7;j--)
{
if(n<7)
{
if(i>0) printf("%3d ",month_day[m]-i+1);
else if(i<=0)
{
if(i>-month_day[m+1]) printf("%3d ",-i+1);
else printf("%3d ",-i-month_day[m+1]+1);
}
i--;
j+=1;
n++;
}
else
{
if(j>0) printf("%3d ",month_day[m+1]-j+1);
else if(j<=0)
{
if(j>-month_day[m+2]) printf("%3d ",-j+1);
else printf("%3d ",-j-month_day[m+2]+1);
}
n++;
}
if(n==14)
{
printf("\n");
n=0;
}
}
printf("=========================== ===========================\n\n");
}

}
void ShowMonth(int week,int year,int month)
{
int i,n,num0=0,nweek0,day=0;
if(year%4==0)
{
if(year%100!=0) month_day[2]=29;
else
{
if(year%400==0) month_day[2]=29;
else month_day[2]=28;
}
}
else month_day[2]=28;
for(int j=1;j!=month;j++)
{
day+=month_day[j];
}
nweek0=(week+day%7)>7?(week+day%7)-7:(week+day%7);
system("CLS");
printf("%-10s %2d\n===========================\nSun Mon Tue Wed Thu Fri Sat\n",month_name[month-1],month);
for(i=nweek0,n=0;i!=nweek0-6*7;i--)
{
if(n<7)
{
if(i>0) printf("%3d ",month_day[month-1]-i+1);
else if(i<=0)
{
if(i>-month_day[month]) printf("%3d ",-i+1);
else printf("%3d ",-i-month_day[month]+1);
}
n++;
}
if(n==7)
{
printf("\n");
n=0;
}
}
printf("===========================\n\n");
}
int startWeek(int year) //确定需要显示的年份的第一天是星期几
{
int start_week,days;
if(year>SIGN_YEAR)
{
days=(year-SIGN_YEAR)*365+(year-SIGN_YEAR)/4-(year-SIGN_YEAR)/100+(year-SIGN_YEAR)/400+(((year-SIGN_YEAR)%4)+3)/4+((year-SIGN_YEAR)%400==0?0:((year-SIGN_YEAR)%100==0?1:0));
start_week=(SIGN_WEEK+days%7)>7?(SIGN_WEEK+days%7)-7:(SIGN_WEEK+days%7);
}
else
{
days=(SIGN_YEAR-year)*365+(SIGN_YEAR-year)/4-(SIGN_YEAR-year)/100+(SIGN_YEAR-year)/400;
start_week=(SIGN_WEEK-days%7)>0?(SIGN_WEEK-days%7):(SIGN_WEEK-days%7+7);
}
return start_week;
}
int main()
{
int year,month,start_week,i;
printf("1.日历\n2.查询\n3.指定月份日历\nSelect:");
scanf("%d",&i);
if(i==1)
{
printf("Enter year:");
scanf("%d",&year);
start_week=startWeek(year);
calendar(start_week,year);
}
else if(i==2)
{
//function 2 code
}
else if(i==3)
{
printf("请指定月份(XXXX－XX):\n");
scanf("%d-%d",&year,&month);
start_week=startWeek(year);
ShowMonth(start_week,year,month);
}
getchar();
getchar();
return 0;
}