c语言编写的万年历 适用初学者

# include "stdio.h" 
int week(int y,int m,int d); 
void main() 
{ 
 int monthday[12]={31,28,31,30,31,30,31,31,30,31,30,31}; 
 int y,w,i,m=1,d=1; 
 int ch;
 do{ 
 printf("请输入一个年份（如：2009）：\n"); 
     scanf("%d",&y); 
     if (y%4==0&&y%100!=0) monthday[1]=29; 
      for(m=1;m<=12;m++) 
  { 
  printf("\n %d年,%d月\n",y,m); 
          printf("S M T w T F S \n"); 
          for (d=1;d<=monthday[m-1];d++) 
  {  
  w=week(y,m,d); 
              if(d==1) 
  { 
  for (i=0;i<w;i++) printf(" "); 
  } 

              if(d<10) printf("%d ",d); 
              else printf("%d ",d); 
              if(w==6) printf(" \n"); 
  } 
  }
  printf("\n Do you wish to continue?(1-continue,2-exit):");
      scanf("%d",&ch);