程序代码：

#include <time.h>
#include<stdio.h>
void week(time_t year,time_t month);
main()
{
  time_t year,month;
  printf("\nInput year,month:\n");
  scanf("%ld,%ld",&year,&month);
  printf("OK!\n");
  week(year,month);
}
void week(time_t year,time_t month)
{
  struct tm *gm;
  char *sTime,sMon[4],spaces[31];
  time_t days,aday,secs,secs1,feb,leaps;
  int date,line,indent,i;

  /*Due to leap year,February has 29 days?*/
  feb=28L;
  if(leap(year)>0) feb=29L;


  days=0L;
  aday=86400L;/* One day's seconds.*/

  /*Days passed before this month in this year.*/
  switch(month)
  {
    case 12L:days=days+30L;/* November */
    case 11L:days=days+31L;
    case 10L:days=days+30L;
    case 9L:days=days+31L;
    case 8L:days=days+31L;
    case 7L:days=days+30L;
    case 6L:days=days+31L;
    case 5L:days=days+30L;
    case 4L:days=days+31L;
    case 3L:days=days+feb;
    case 2L:days=days+31L;
      break;
    default:;
  }

  /*Add up leap days since 1970.*/
  for(leaps=1970L;leaps<year;leaps++)
  {
    if(leap(leaps)>0)
    {
      days=days+1L;
    }
  }
  line=0;
  sMon[0]='\0';

  printf("\n\n Weeks of %ld.%ld :\n",month,year);
  printf("  SUN  MON  TUE  WED  THU  FRI  SAT");

  date=1;
  year=year-1970L;
  year=year*365L*aday;
  month=days*aday;

  secs=year+month;
  secs1=secs;
  gm=gmtime(&secs1);
  sTime=asctime(gm);

  /*Determine spaces for aligning for the 1st day.*/
  indent=0;
  if(sTime[0]=='M'&&sTime[1]=='o'&&sTime[2]=='n')
  {
    indent=5;
    line=1;
  }
  if(sTime[0]=='T'&&sTime[1]=='u'&&sTime[2]=='e')
  {
    indent=10;
    line=2;
  }
  if(sTime[0]=='W'&&sTime[1]=='e'&&sTime[2]=='d')
  {
    indent=15;
    line=3;
  }
  if(sTime[0]=='T'&&sTime[1]=='h'&&sTime[2]=='u')
  {
    indent=20;
    line=4;
  }
  if(sTime[0]=='F'&&sTime[1]=='r'&&sTime[2]=='i')
  {
    indent=25;
    line=5;
  }
  if(sTime[0]=='S'&&sTime[1]=='a'&&sTime[2]=='t')
  {
    indent=30;
    line=6;
  }

  for(i=0;i<indent;i++)
  {
    spaces[i]=' ';
  }
  spaces[i]='\0';

  if(indent>0)
  {
    printf("\n%s",spaces);
  }


  sMon[0]=sTime[4];
  sMon[1]=sTime[5];
  sMon[2]=sTime[6];

  /* Just show this month. */
  while(sMon[0]==sTime[4]&&sMon[1]==sTime[5]&&sMon[2]==sTime[6])
  {
    if(line%7==0)
    {
      printf("\n");
    }
    printf("  %3d",date);
    line++;

    sMon[0]=sTime[4];
    sMon[1]=sTime[5];
    sMon[2]=sTime[6];

    date++;
    secs=secs+aday;
    secs1=secs;
    gm=gmtime(&secs1);
    sTime=asctime(gm);
  }

}

int leap(long year)
{
  if(year%4==0&&year%100!=0||year%400==0)
  {
    return 1;
  }
  return -1;
}