C语言实现简单万年历

#include <stdio.h>
#include<stdlib.h>
int year, month;
int run[12] = { 31,29,31,30,31,30,31,31,30,31,30,31 };
int ping[12] = { 31,28,31,30,31,30,31,31,30,31,30,31 };
char week[7][10] = { "SUN","MON","TUE","WED","THU","FRI","SAT" };
bool IsLeap(int year)
{
 if (year % 400 == 0 || (year % 4 == 0 && year % 100 != 0)) //判断闰年
 {
 return true;
 }
 else
 {
 return false;
 }
}
void PrintStar()
{
 printf("\t\t\t万年历\t\t\t\n");
 printf("****************************************************\n");
 for (int i = 0; i < 7; i++)
 {
 printf("%s\t", week[i]);
 }
 printf("\n");
}
int DaySum(int year, int month)
{
 int sum = 0;
 for (int i = 1990; i < year; i++)
 {
 if (IsLeap(i))
 {
 sum += 366;
 }
 else
 {
 sum += 365;
 }
 }
 for (int i = 0; i < month - 1; i++)
 {
 if (IsLeap(year))
 {
 sum += run[i];
 }
 else
 {
 sum += ping[i];
 }
 }
 return sum;
}
void PrintCal(int sum, int year, int month)
{
 int nRes, nTmp;
 nRes = sum % 7+1;//前面空几格
 nTmp = 7 - nRes;//从第几格开始打印
 for (int i = 0; i < nRes; i++)
 {
 printf("\t");
 }
 if (IsLeap(year))
 {
 for (int i = 1; i < run[month - 1]+1; i++)
 {
 printf("%d\t", i);
 if (nTmp == i || (i - nTmp) % 7 == 0)
 {
 printf("\n");
 }
 }
 printf("\n");
 }
 else
 {
 for (int i = 1; i < ping[month - 1]+1; i++)
 {
 printf("%d\t", i);
 if (nTmp == i || (i - nTmp) % 7 == 0)
 {
 printf("\n");
 }
 }
 printf("\n");
 }
}
int main(void)
{
 while (1)
 {
 scanf_s("%d %d", &year, &month);
 PrintStar();
 PrintCal(DaySum(year, month), year, month);
 printf("****************************************************\n");
 }
 return 0;
}