Implement Queue using Array.

C: Program that implements queue as an array.

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

#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 ;
}