Program that implements queue as an array.

#include
#include

#define MAX 10

void addq ( int *, int, int *, int * ) ;
int delq ( int *, int *, int * ) ;

void main( )
{
int arr[MAX] ;
int front = -1, rear = -1, i ;

clrscr( ) ;

addq ( arr, 23, &front, &rear ) ;
addq ( arr, 9, &front, &rear ) ;
addq ( arr, 11, &front, &rear ) ;
addq ( arr, -10, &front, &rear ) ;
addq ( arr, 25, &front, &rear ) ;
addq ( arr, 16, &front, &rear ) ;
addq ( arr, 17, &front, &rear ) ;
addq ( arr, 22, &front, &rear ) ;
addq ( arr, 19, &front, &rear ) ;
addq ( arr, 30, &front, &rear ) ;
addq ( arr, 32, &front, &rear ) ;

i = delq ( arr, &front, &rear ) ;
printf ( "\nItem deleted: %d", i ) ;

i = delq ( arr, &front, &rear ) ;
printf ( "\nItem deleted: %d", i ) ;

i = delq ( arr, &front, &rear ) ;
printf ( "\nItem deleted: %d", i ) ;

getch( ) ;
}

/* adds an element to the queue */
void addq ( int *arr, int item, int *pfront, int *prear )
{
if ( *prear == MAX - 1 )
{
printf ( "\nQueue is full." ) ;
return ;
}

( *prear )++ ;
arr[*prear] = item ;

if ( *pfront == -1 )
*pfront = 0 ;
}

/* removes an element from the queue */
int delq ( int *arr, int *pfront, int *prear )
{
int data ;

if ( *pfront == -1 )
{
printf ( "\nQueue is Empty." ) ;
return NULL ;
}

data = arr[*pfront] ;
arr[*pfront] = 0 ;
if ( *pfront == *prear )
*pfront = *prear = -1 ;
else
( *pfront )++ ;

return data ;
}