额。写过，我去找找
#include<stdio.h>
void PrintMonthCalender(int startDay,int days);/*函数原型*/
int GetWeekDay(int year,int month);/*函数原型*/
int GetMonthDays(int year,int month);/*函数原型*/
main()
{
 int month,year;/*定义变量*/

 printf("input the year and month<YYYY-MM>:");
 scanf("%d-%d",&year,&month);/*读入变量*/
 printf("\t\t\t%d-%d\n",year,month);
 printf("Sun.\tMon.\tTue.\tWed.\tThu.\tFri.\tSat.\n");/*打印日历表头*/
 
 PrintMonthCalender(GetWeekDay(year,month),GetMonthDays(year,month));/*调用函数子程序，打印出某年某月日历*/
   
    return 0;
}

/*定义打印日历子程序*/
void PrintMonthCalender(int startDay,int days)
{
 int k=0,n=1;
 
 while(k<startDay)
 {
  printf(" \t");
  k++;
 }

 if(k==startDay&&k!=6)
 {
  printf("%d\t",n);
  k++;
  n++;
 }
 else if(k==startDay&&k==6)
 {
  printf("%d\n",n);
  k++;
  n++;
 }
 while(n<days)
 {
  if(k%7==6)
  {
   printf("%d\n",n);
   k++;
   n++;
  }
  else
  {
   printf("%d\t",n);
   k++;
   n++;
   }
 }
  if(n=days)
  {
   printf("%d\n",n);
      n++;
  }

}

/*定义求某月一号为周几子程序*/
int GetWeekDay(int year,int month)

{   
 int GetMonthDays(int year,int month);
 int n,WeekDay,days;

 days=(year-1)*365+(year-1)/400+(year-1)/4-(year-1)/100;
 
  for(n=1;n<month;++n)
  
   days=days+GetMonthDays(year,n);
   
  WeekDay=(days+1)%7;

 return WeekDay;
}

/*定义求某年某月的天数子程序*/
int GetMonthDays(int year,int month)
{
 int MonthDays;
 if((year%4==0&&year%100!=0)||year%400==0)
 {
  if(month==4||month==6||month==9||month==11)
   MonthDays=30;
  else if(month==2)
   MonthDays=29;
  else
   MonthDays=31;
 }
  
 else
 {
   if(month==4||month==6||month==9||month==11)
   MonthDays=30;
  else if(month==2)
   MonthDays=28;
  else
   MonthDays=31;
 }
 return MonthDays;
}