fun_date.c

计算一个日期n天后或n天前的日期是多少

#include <stdio.h>

typedef struct Date 
{
 char   YYYY   [ 5 ];
 char   MM     [ 3 ];
 char   DD     [ 3 ];
}DATE ;

void RelativeDate  (  char *pInDate , char *pOutDate , long n );

int main(int argc, char *argv[])
{
  char *tim ;
  char tim1[10] ;

  tim=argv[1] ;
  
  RelativeDate ( tim , tim1 ,-1 ) ; 
  
  printf("%s\n",&tim1[4]);
}
  

/*TION NAME ： RelativeDate ( char *pInDate , char *pOutDate , long n )
 * Usage:  pInDate  char [9],  pOutDate char [9] , n  long
 *         起始日期            输出日期            间隔天数
 * Disc :  计算起始日期的n天后的日期
 * OUTPUT：THE OUTPUT IS pOutDate is the date after  n days of InDate
 *********************************************************************/

void RelativeDate  (  char *pInDate , char *pOutDate , long n )
{
   unsigned short     Year       ;
   unsigned short     Mon        ;
   unsigned short     Day        ;
   DATE               StartDate  ;
   DATE               EndDate    ;
   short              rc         ;
   unsigned long      i          ;
   char               TmpStr [4] ;
   
   i = 0 ;

   #ifdef  DEBUG
      printf ( "%s\n", pInDate  );
   #endif
      
   memset ( StartDate . YYYY , 0x00,  5  );
   memset ( StartDate . MM ,   0x00,  3  );
   memset ( StartDate . DD ,   0x00,  3  );
   
   memcpy ( StartDate . YYYY , pInDate , 4 );
   memcpy ( StartDate . MM ,   pInDate + 4 , 2 );
   memcpy ( StartDate . DD ,   pInDate + 6 , 2 );

   #ifdef DEBUG
      printf ( "%s+++%s+++%s\n",  StartDate . YYYY ,  StartDate . MM ,  
               StartDate . DD  );
   #endif
   
   Year = atoi ( StartDate . YYYY  );
   Mon  = atoi ( StartDate . MM    );
   Day  = atoi ( StartDate . DD    );

   #ifdef DEBUG
      printf ( "%d---%d---%d\n", Year , Mon , Day  );
   #endif
 
   if ( n == 0 )
   {
      strcpy (  pOutDate , pInDate );
      return ;	
   }	
   
   if ( n > 0 )
   {
      for ( ;; )
      {
         if ( i < n )
         {
            i ++ ;
       	    Day = Day + 1 ;
   	     
   	    rc = f_Is_Nleapyear ( Year );
   	    if ( rc == 0 )
   	    {
   	       if ( ( Day == 29 ) && ( Mon == 2 ) )
   	       {
   	          Day = 1 ;
   	          Mon = Mon + 1 ;
   	       }
   	    }
   	    else
   	    {
   	       if ( ( Day == 30 ) && ( Mon == 2 ) )
   	       {
   	          Day = 1 ;
   	          Mon = Mon + 1 ;
   	       }
   	    }
   	     
   	    if ( ( Day == 31 ) && ( Mon == 4 ||  Mon == 6 || Mon == 9 ||
   	                            Mon == 11 ) )
   	    {
   	       Day = 1 ;
   	       Mon = Mon + 1 ;
   	    }
   	     
   	    if ( ( Day == 32 ) && ( Mon == 1 || Mon == 3 ||  Mon == 5 ||
   	                            Mon == 7 || Mon == 8 || Mon == 10 ) )
   	    {
   	       Day = 1 ;
   	       Mon = Mon + 1 ;
   	    }
   	     
   	    if (  Day == 32 &&  Mon == 12 )
   	    {
   	       Day = 1 ;
   	       Mon = 1 ;
   	       Year = Year + 1 ;
   	    }
   	 }
   	 else
         {
   	    break ;
         }
      }       
   }	

   if ( n < 0 )
   {
      n = 0 - n  ;
      for ( ;; )
      {
         if ( i < n )
   	 {
            i ++ ;
       	    Day = Day - 1 ;
   	     
   	    rc = f_Is_Nleapyear ( Year );
   	    if ( rc == 0 )
   	    {
   	       if ( ( Day == 0 ) && ( Mon == 3 ) )
   	       {
   	          Day = 28 ;
   	          Mon = Mon - 1 ;
   	       }
   	    }
   	    else
   	    {
   	       if ( ( Day == 0 ) && ( Mon == 3 ) )
   	       {
   	          Day = 29 ;
   	          Mon = Mon - 1 ;
   	       }
   	    }
   	     
   	    if ( ( Day == 0 ) && ( Mon == 2 || Mon == 4 ||  Mon == 6 || 
   	                           Mon == 9 || Mon == 8  || Mon == 11 ) )
   	    {
   	       Day = 31 ;
   	       Mon = Mon - 1 ;
   	    }
   	     
   	     
   	    if ( ( Day == 0 ) && ( Mon == 12 || Mon == 5 || Mon == 7 ||
   	                           Mon == 10 ) )
   	    {
   	       Day = 30 ;
   	       Mon = Mon - 1 ;
   	    }
   	     
   	    if (  Day == 0 &&  Mon == 1 )
   	    {
   	       Day = 31 ;
   	       Mon = 12 ;
   	       Year = Year - 1 ;
   	    }
         }
   	 else
   	    break ;
      }
   }

   #ifdef  DEBUG
      printf ( "%d---%d---%d\n", Year , Mon , Day  );
   #endif

   memset ( pOutDate , 0x00 , sizeof ( pOutDate ) ) ;
   memset ( TmpStr ,   0x00 , sizeof ( TmpStr   ) ) ;
   
   sprintf( TmpStr, "%04d%02d%02d", Year ,  Mon  , Day );  
       
   strcpy ( pOutDate ,  TmpStr ) ;
          
  
   return ;   
}

/*  TION NAME ：int  f_Is_Nleapyear ( unsigned short YYYY )
 * Usage: YYYY 是年份转换成的整数           
 * Discription: 检查YYYY是否闰年
 * OUTPUT: 0 - No, 0  - Yes , 
 *********************************************************************/

int  f_Is_Nleapyear ( unsigned short YYYY )
{
   unsigned short           nian    ;
   unsigned short           N1      ;
   unsigned short           N2      ;
   unsigned short           N3      ;
   
    
    nian =  YYYY ;
    N1 = nian % 4 ;
    N2 = nian % 100 ;
    N3 = nian % 400 ;
    if ((( N1 == 0 ) && ( N2 != 0 )) || ( ( N2 == 0 ) && ( N3 == 0 ) ) )
        return 1 ;
     
    return 0 ;
}