show current status, i.e. the floor no.

/* show current status, i.e. the floor no. on which the lifts are standing */

A program that demonstrates how an array can be used to show working of lifts in a multi-storeyed building.

A 30- storeyed building has got about 5 wings where there would be a lift in each of the wing. You have to make available a lift to the person who presses a button to get a lift. Follow the steps given below for designing the program.

1. The floors of the building should be numbered as 0 - 29.
2. The lifts should be numbered as 0 - 4.
3. Display a menu that would have following options
a. Do you wish to use a lift?
b. Show lift status
c. Exit
If user selects, option 1 then get following information from the user.

-Get the floor number where the person is standing
-Whether user wishes to go up/down.
-Get the floor number where the user wishes to go.

The validation checks should be there for the data that user enters.
The validation checks are as given below.
1. The floor number where the user is standing and the floor number where user wishes to go should be in a range of 0 to 29.
2. If the user is standing on ground floor, i.e. 0th floor, then selecting the direction for the lift to go down would be invalid.
3. If the user is standing on topmost floor, i.e. 29th floor, then selecting the direction for the lift to go up would be invalid.
4. The direction for the lift whether up or down should be entered as 'u' or 'd' only.

Check for the lift that can be made available to the person. Before making a lift available to the user consider the following.

1. The lift, which is nearer to the user, i.e., the floor where he is standing should be made available.
2. If the user is standing on a floor, say 8th floor for example. And there are two lifts one on the 7th floor and the other on the 9th floor. Both the lifts are nearer to the user. In such a situation, first check where the user wishes to go, up/down? If up then the lift on the 7th floor should be made available. And if down then the lift on 9th floor should be made available.
2. If the user is standing on say 4th floor for example. And there are 3 lifts, lift number 0, 2, and 4, standing on the 0th floor. All the three are nearer to the user. In such a situation lift that comes first in the order should be made available.

#include <stdio.h>
#include <conio.h>
#include <stdlib.h>
#include <conio.h>
#include <dos.h>
#include <ctype.h>
#include <math.h>

void showstatus( ) ;
void allotlift ( int *, int, int, char ) ;

/* show current status, i.e. the floor no. on which
the lifts are standing */
void showstatus ( int *lf )
{
int i ;

for ( i = 0 ; i < 5 ; i++ )
printf ( "Lift : %d is on %d floor\n", i, lf[i] ) ;
}

/* allot the lift to the user */
void allotlift ( int *lf, int flnos, int flnot, char d )
{
/* struct p to store the difference between 2 lifts */
struct p
{
int lfno[5] ;
int pos[5] ;
int diff[5] ;
} arr ;

int lno = -1 ; /* to store the lift no. that can be made available */
int i, j, k, t1, t2, t3 ;

/* initialize array */
for ( i = 0; i < 5; i++ )
{
arr.lfno[i] = i ;
arr.pos[i] = 0 ;
arr.diff[i] = 0 ;
}

while ( lno == -1 )
{
/* get the current position of a lift */
for ( i = 0 ; i < 5; i++ )
arr.pos[i] = lf[i] ;

for ( i = 0; i < 5; i++ )
{
/* get the diff. between floor on which lift is standing
and the floor on which the user is standing */
arr.diff[i] = abs ( arr.pos[i] - flnos ) ;
}

/* sort array */
for ( i = 0; i < 5; i++ )
{
for ( j = 0; j < 4; j++ )
{
if ( arr.diff[i] < arr.diff[j] )
{

t1 = arr.lfno[i] ;
t2 = arr.pos[i] ;
t3 = arr.diff[i] ;
arr.lfno[i] = arr.lfno[j] ;
arr.pos[i] = arr.pos[j] ;
arr.diff[i] = arr.diff[j] ;
arr.lfno[j] = t1 ;
arr.pos[j] = t2 ;
arr.diff[j] = t3 ;
}
}
}

/* check for the lift that can be alloted
depending on the direction */
for ( i = 0, k = 0; i < 5; i++ )
{
k = arr.lfno[i] ;

if ( ( d == 'u' ) && (
( lf[k] < flnos ) ||
( lf[k] == 0 ) ||
( lf[k] == flnos ) ) )
{
lno = k ;
break ;
}

if ( ( d == 'd' ) && (
( lf[k] > flnos ) ||
( lf[k] == 0 ) ||
( lf[k] == flnos ) ) )
{
lno = k ;
break ;
}
}

/* if none of the lift has been alloted */
j = 30 ;
if ( lno == -1 )
{
for ( i = 0; i < 5; i++ )
{
if ( j > arr.diff[i] )
{
j = arr.diff[i] ;
lno = i ;
}
}
}
}

printf ( "\nThe lift available to you would be: %d\n\n", lno ) ;

lf[lno] = flnot ;
}

/* the main menu */
int showmenu( )
{
int c ;

printf ( " -------------------- Lift Program -------------------- \n" ) ;
printf ( " There are 5 lifts available for your service. \n" ) ;
printf ( " Select 1 if you want to use a lift. \n" ) ;
printf ( " Selecting 2 would show, for each of the 5 lifts, \n" ) ;
printf ( " the floor no. on which the lift is currently standing. \n" ) ;
printf ( " Select 3 to quit the program \n" ) ;
printf ( " ------------------------------------------------------ \n" ) ;
printf ( " 1. Do you wish to use lift?\n" ) ;
printf ( " 2. Show status of lift\n" ) ;
printf ( " 3. Exit\n" ) ;
printf ( " ------------------------------------------------------ \n" ) ;
scanf ( "%d", &c ) ;

return c ;
}

void validate ( int *fs, int *ft, char *d )
{
int flnos, flnot ;
char dir ;
int flag ;
unsigned char chr ;

flnos = flnot = -1 ;
flag = 0 ;

while ( flnos < 0 || flnos > 29 )
{
printf ( "Enter the floor no. where you are standing : " ) ;
scanf ( "%d", &flnos ) ;

if ( flnos < 0 || flnos > 29 )
{
printf ( "\nIncorrect floor no.! Enter floor no. in a range of 0 - 29 \n\n" ) ;
getch( ) ;
}
}

while ( flag == 0 )
{
dir = 'j' ;
while ( tolower ( dir ) != 'u' && tolower ( dir ) != 'd' )
{
printf ( "Do you wish to go up or down (up/down): " ) ;
fflush ( stdin ) ;
scanf ( "%c", &dir ) ;
printf ( "\n" ) ;

if ( dir != 'u' && dir != 'd' )
printf ( "Incorrect direction! Enter again\n" ) ;
}

if ( flnos == 0 && dir == 'd' )
{
printf ( "\nYou are already standing on ground floor.\n" ) ;
printf ( "Cannot go further down.\n" ) ;
getch( ) ;
flag = 0 ;
}
else
flag = 1 ;
}
flag = 0 ;

while ( flag == 0 )
{
printf ( "\nEnter the floor no. where you want to go: " ) ;
scanf ( "%d", &flnot ) ;

if ( ( flnos == 0 && flnot == 0 ) ||
( flnot < 0 || flnot > 29 ) ||
( flnos == flnot ) ||
( ( flnos != 0 ) && ( dir == 'd' && ( flnos - flnot < 0 ) ) ) ||
( ( flnos != 0 ) && ( dir == 'u' && ( flnot < flnos ) ) ) )
{
printf ( "\nIncorrect floor no. or trying to move to the same \n" ) ;
printf ( "floor where you are standing, or either the \n" ) ;
printf ( " direction given is incorrect or the floor number \n" ) ;
printf ( " is incorrect. Try again \n") ;
flag = 0 ;
}
else
flag = 1 ;
}

*fs = flnos ;
*d = dir ;
*ft = flnot ;
}

void main( )
{
int ch ; /* stores the no. entered as a choice for the menu */
int flnos ; /* to store floor no. where the user stands */
int flnot ; /* to store the target floor no. */
char dir ; /* to store the direction */
char chr[20] ; /* a temporary variable */
int lf[5] = { 0, 0, 0, 0, 0 } ;

void validate ( int *, int *, char * ) ;

flnos = flnot = -1 ;

clrscr( ) ;

while ( 1 )
{
/* display main menu */
ch = showmenu( ) ;

/* switch-case for menu options to be handled */
switch ( ch )
{
case 1 :

/* actual program logic */
printf ( "Allot lift: \n" ) ;
validate ( &flnos, &flnot, &dir ) ;
allotlift ( lf, flnos, flnot, dir ) ;
break ;

case 2 :

/* getstaus */
printf ( "Current status of lifts: \n" ) ;
showstatus ( lf ) ;
break ;

case 3 :

/* exit program */
exit ( 0 ) ;
break ;

default :

/* wrong choice */
printf ( "Incorrect choice! try again!" ) ;
}

printf ( "\n\n" ) ;
printf ( "Press key to continue..." ) ;
fflush ( stdin ) ;
scanf ( "%c", &chr ) ;
}
}