#include <stdio.h>
#include <conio.h>
#include <stdlib.h>
#include <string.h>

int d, m ;
longint y ;

void main( )
{
    char dates[5][12], temp[12] ;
    longint arr[5], t ;
    int i, j, valid ;

    int isvalid( ) ;
    longint getnum ( char * ) ;

    clrscr( ) ;

    printf ( "Enter any five dates (dd\\mm\\yyyy) :-\n" ) ;
    for ( i = 0 ; i <= 4 ; i++ )
    {
        printf("%d) ",i + 1 ) ;
        scanf ( "%s", dates[i] ) ;

        /* Converts date in string to equivalent integer values. */

        arr[i] = getnum ( dates[i] ) ;

        /* Checks for valid date. */

        valid = isvalid( ) ;

        if ( !valid )
        {
            printf ( "This date does not exists. " ) ;
            printf ( "Enter any other date.\n" ) ;
            i-- ;
        }
    }

    /* Sorting of dates using Bubble sort method. */
for ( i = 0 ; i <= 3 ; i++ )
    {
        for ( j = 0 ; j <= 3 - i ; j++ )
        {
            if ( arr[j] > arr[j + 1] )
            {
                t = arr[j] ;
                arr[j] = arr[j + 1] ;
                arr[j + 1] = t ;

                strcpy ( temp, dates[j] ) ;
                strcpy ( dates[j], dates[j + 1]) ;
                strcpy ( dates[j + 1], temp ) ;
            }
        }
    }

    printf ( "Dates in sorted order are :- \n" ) ;
    for ( i = 0 ; i <= 4 ; i++ )
        printf ( "%s\n", dates[i] ) ;

    getch( ) ;
}

/* checks valid date */
int isvalid ( )
{
    int isleap ( longint ) ;

    if ( y <= 0 || m <= 0 || d <= 0 || m > 12 || y > 16384 ||
         ( m == 2 && !isleap ( y ) && d > 28 ) ||
         ( m == 2 && isleap ( y ) && d > 29 ) ||
         ( ( m == 1 || m == 3 || m == 5 || m == 7 || m == 8 || m == 10
          || m == 12 ) && d > 31 ) || ( ( m == 4 || m == 6 || m == 9 ||
             m == 11 ) && d > 30 ) )
        return 0 ;
    elsereturn 1 ;
}

/* checks whether the given year is leap or not */
int isleap ( longint y )
{
    return ( y % 4 == 0 ) ^ ( y % 100 == 0 ) ^ ( y % 400 == 0 ) ;
}

/* converts dates in string into equivalent integer values */
longint getnum ( char *date )
{
    char *p, str[15] ;
    longint num = 0 ;

    strcpy ( str, date ) ;

    d = m = y = 0 ;
    p = strtok ( str, "\\" ) ;
    if ( p != NULL )
        d = num = atoi ( p )  ;

    p = strtok(NULL, "\\");
    if ( p != NULL )
        m = atoi ( p ) ;
    num += m * 32 ;

    p = strtok(NULL, "\\");
    if ( p != NULL )
        y = atol ( p ) ;
    num += y * 512L ;

    return num ;
}