#include <stdio.h> #include <conio.h> #include <alloc.h> #define MAX 10 struct dqueue { int arr[MAX] ; int front, rear ; } ; void initdqueue ( struct dqueue * ) ; void addqatbeg ( struct dqueue *, int ) ; void addqatend ( struct dqueue *, int ) ; int delqatend ( struct dqueue * ) ; void display ( struct dqueue ) ; int count ( struct dqueue ) ; void main( ) { struct dqueue dq ; int i, n ; clrscr( ) ; initdqueue ( &dq ) ; addqatend ( &dq, 11 ) ; addqatbeg ( &dq, 10 ) ; addqatend ( &dq, 12 ) ; addqatbeg ( &dq, 9 ) ; addqatend ( &dq, 13 ) ; addqatbeg ( &dq, 8 ) ; addqatend ( &dq, 14 ) ; addqatbeg ( &dq, 7 ) ; addqatend ( &dq, 15 ) ; addqatbeg ( &dq, 6 ) ; addqatend ( &dq, 16 ) ; addqatbeg ( &dq, 5 ) ; display ( dq ) ; n = count ( dq ) ; printf ( \"\\nTotal elements: %d\", n ) ; i = delqatend ( &dq ) ; printf ( \"\\nItem extracted = %d\", i ) ; i = delqatend ( &dq ) ; printf ( \"\\nItem extracted = %d\", i ) ; i = delqatend ( &dq ) ; printf ( \"\\nItem extracted = %d\", i ) ; i = delqatend ( &dq ) ; printf ( \"\\nItem extracted = %d\", i ) ; n = count ( dq ) ; printf ( \"\\nElements Left: %d\", n ) ; display ( dq ) ; addqatbeg ( &dq, 5 ) ; addqatbeg ( &dq, 4 ) ; addqatbeg ( &dq, 3 ) ; addqatbeg ( &dq, 2 ) ; display ( dq ) ; getch( ) ; } /* initializes elements of structure */ void initdqueue ( struct dqueue *p ) { int i ; p -> front = p -> rear = -1 ; for ( i = 0 ; i < MAX ; i++ ) p -> arr[i] = 0 ; } /* adds item at begining of dqueue */ void addqatbeg ( struct dqueue *p, int item ) { int c, i, k ; if ( p -> front == 0 && p -> rear == MAX ) { printf ( \"\\nQueue is full.\\n\" ) ; return ; } if ( p -> front == -1 && p -> rear == -1 ) { p -> front = p -> rear = 0 ; p -> arr[p -> front] = item ; return ; } if ( p -> rear != MAX ) { c = count ( *p ) ; k = p -> rear ; for ( i = 1 ; i <= c ; i++ ) { p -> arr[k] = p -> arr[k - 1] ; k-- ; } p -> arr[k] = item ; p -> front = k ; ( p -> rear )++ ; } else { ( p -> front )-- ; p -> arr[p -> front] = item ; } } /* adds item at the end of dqueue */ void addqatend ( struct dqueue *p, int item ) { int i, k ; if ( p -> front == 0 && p -> rear == MAX ) { printf ( \"\\nQueue is full.\\n\" ) ; return ; } if ( p -> rear == -1 && p -> front == -1 ) { p -> rear = p -> front = 0 ; p -> arr[p -> rear] = item ; ( p -> rear )++ ; return ; } if ( p -> rear == MAX ) { k = p -> front - 1 ; for ( i = p -> front - 1 ; i < p -> rear ; i++ ) { k = i ; if ( k == MAX - 1 ) p -> arr[k] = 0 ; else p -> arr[k] = p -> arr[i + 1] ; } ( p -> rear )-- ; ( p -> front )-- ; } p -> arr[p -> rear] = item ; ( p -> rear )++ ; } /* deletes item from end of dqueue */ int delqatend( struct dqueue *p ) { int item ; if ( p -> front == -1 && p -> rear == -1 ) { printf ( \"\\nQueue is empty.\\n\" ) ; return 0 ; } ( p -> rear )-- ; item = p -> arr[p -> rear] ; p -> arr[p -> rear] = 0 ; if ( p -> rear == 0 ) p -> rear = -1 ; return item ; } /* displays the queue */ void display( struct dqueue dq ) { int i ; printf ( \"\\n front -> \" ) ; for ( i = 0 ; i < MAX ; i++ ) printf ( \"\\t%d\", dq.arr[i] ) ; printf ( \" <- rear \" ) ; } /* counts the number of items in dqueue */ int count( struct dqueue dq ) { int c, i ; for ( i = c = 0 ; i < MAX ; i++ ) { if ( dq.arr[i] != 0 ) c++ ; } return c ; }