《C语言的科学与艺术》学习笔记之万年历代码

来源：互联网发布：如何自学大数据编辑：程序博客网时间：2024/05/16 18:18

万年历算法：根据具体的某一天的真实日期及星期为基点，往前往后运算。

#include <stdio.h>
#include <genlib.h>
#include <simpio.h>

#define Sunday    0
#define Monday    1
#define Tuesday   2
#define Wednesday 3
#define Thursday  4
#define Friday    5
#define Saturday  6

void GiveInstructions(void);
int GetYearFromUser(void);
void PrintCalendar(int year);
void PrintCalendarMonth(int month,int year);
void IndentFirstLine(int weekday);
int MonthDays(int month,int year);
int FirstDayOfMonth(int month,int year);
string MonthName(int month);
bool IsLeapYear(int year);

//主函数
main()
{
int year;

GiveInstructions();
year=GetYearFromUser();
PrintCalendar(year);
}

//程序说明

void GiveInstructions(void)
{
printf("This program displays a calendar for a full\n");
printf("year. The year must not be before 1900.\n");
}

//获取年份

int GetYearFromUser(void)
{
int year;

while (TRUE)
{
  printf("Which year?");
  year=GetInteger();
  if (year>=1900) return (year);
  printf("The year must be at least 1900.\n");
}
}

//打印日历函数

void PrintCalendar(int year)
{
int month;

for (month=1;month<=12;month++)
{
PrintCalendarMonth(month,year);
printf("\n");
}
}

//打印月份

void PrintCalendarMonth(int month,int year)
{
int weekday,nDays,day;

printf("    %s %d\n",MonthName(month),year);
printf(" Su Mo Tu We Th Fr Sa\n");
nDays=MonthDays(month,year);
weekday=FirstDayOfMonth(month,year);
IndentFirstLine(weekday);
for (day=1;day<=nDays;day++)
{
  printf(" -",day);
  if (weekday==Saturday)
  {
   printf("\n");
  }
  weekday=(weekday+1)%7;
}
if (weekday!=Sunday)
{
  printf("\n");
}
}

//显示第一行

void IndentFirstLine(int weekday)
{
int i;

for (i=0;i<weekday;i++)
{
printf(" ");
}
}

//计算月份的天数

int MonthDays(int month,int year)
{
switch (month)
{
  case 2:
   if (IsLeapYear(year))
   {
    return (29);
   }
   return (28);
  case 4:
  case 6:
  case 9:
  case 11:
   return(30);
  default:
   return (31);
}
}

//计算月份中第一天是星期几

int FirstDayOfMonth(int month,int year)
{
int weekday,i;

weekday=Monday;
for (i=1900;i<year;i++)
{
  weekday=(weekday+365)%7;
  if(IsLeapYear(i))
   weekday=(weekday+1)%7;
}
for (i=1;i<month;i++)
{
  weekday=(weekday+MonthDays(i,year))%7;
}
return (weekday);
}

//显示月份的名字

string MonthName(int month)
{
switch(month)
{
case   1: return ("January");
case   2: return ("February");
case   3: return ("March");
case   4: return ("April");
case   5: return ("May");
case   6: return ("June");
case   7: return ("July");
case   8: return ("August");
case   9: return ("September");
case  10: return ("October");
case  11: return ("November");
case  12: return ("December");
default:  return ("Illegal month");
}
}

//判断是否为闰年

bool IsLeapYear(int year)
{
return (((year%4==0)&&(year0!=0))||(year@0==0));
}