1. Get the Queue Code that is in your Code folder to run. Modify it so that it enqueues and dequeues integers instead of characters. Note: you will want to modify the main( ), change the Object data type so that it uses an int, and visitChar( ) routine should be renamed and change the %c to %d.

Enqueue at least 3 ints, traverse the queue and print out the contents of the nodes, then dequeue each item separately and print its contents as it is dequeued. Show the number of elements that are in the queue at intervals. (10 points)

/**

*FILENAME: listQueue.c

*PURPOSE: Implements a simple queue data structure using C.

* This queue's data is stored in a linked list.

* Since the queue is passed to the functions as an argument,

* a program can have many different queues.

* This queue can be traversed with the traverseQueue function,

* however the visit function must be different for each

* different datatype stored in the queue.

*DATE: 16-Apr-2005

*PROGRAMMER: Charles Moen

*/

#include

#include

typedef char Object; /*Datatype of the elements in the queue*/

typedef struct node{ /*Nodes stored in the linked list*/

Object element;

struct node *next;

} Node;

typedef struct queue{ /*A struct facilitates passing a queue as an argument*/

Node *head; /*Pointer to the first node holding the queue's data*/

Node *tail; /*Pointer to the last node holding the queue's data*/

int sz; /*Number of nodes in the queue*/

} Queue;

int size( Queue *Q ){

return Q->sz;

}

int isEmpty( Queue *Q ){

if( Q->sz == 0 ) return 1;

return 0;

}

void enqueue( Queue *Q, Object elem ){

Node *v = (Node*)malloc(sizeof(Node));/*Allocate memory for the Node*/

if( !v ){

printf("ERROR: Insufficient memory ");

return;

}

v->element = elem;

v->next = NULL;

if( isEmpty(Q) ) Q->head = v;

else Q->tail->next = v;

Q->tail = v;

Q->sz++;

}

Object dequeue( Queue *Q ){

Node *oldHead;

Object temp;

if( isEmpty(Q) ){

printf("ERROR: Queue is empty ");

return 0;

}

oldHead = Q->head;

temp = Q->head->element;

Q->head = Q->head->next;

free(oldHead);

Q->sz--;

return temp;

}

Object first( Queue *Q ){

if( isEmpty(Q) ){

printf("ERROR: Queue is empty ");

return 0;

}

return Q->head->element;

}

void destroyQueue( Queue *Q ){

while( !isEmpty(Q) ) dequeue(Q);

}

/*A different visit function must be used for each different datatype.*/

/*The name of the appropriate visit function is passed as an argument */

/*to traverseQueue. */

void visitChar( Object elem ){

printf("%c ",elem);

}

/*The following function isn't part of the Queue ADT, however*/

/*it can be useful for debugging. */

void traverseQueue( Queue *Q, void (*visit)(Object elem) ){

Node *current = Q->head;

while( current ){

visit(current->element);

current = current->next;

}

printf(" ");

}

/*Sample code that demonstrates the queue*/

int main( int argc, char *argv[] ){

/*Declare a queue and initialize its fields*/

Queue Q;

Q.head = NULL;

Q.tail = NULL;

Q.sz = 0;

printf("Enqueueing three chars, abc ");

enqueue(&Q,'a');

enqueue(&Q,'b');

enqueue(&Q,'c');

printf("Size = %d ",size(&Q));

printf("isEmpty = %d ",isEmpty(&Q));

printf("First = %c ",first(&Q));

printf("Traversing the queue: ");

traverseQueue(&Q,visitChar);

printf("Dequeueing two chars: ");

printf("%c",dequeue(&Q));

printf("%c ",dequeue(&Q));

printf("Size = %d ",size(&Q));

printf("First = %c ",first(&Q));

printf("Dequeueing one char: ");

printf("%c ",dequeue(&Q));

printf("Size = %d ",size(&Q));

printf("isEmpty = %d ",isEmpty(&Q));

printf("Attempting to dequeue one char: ");

dequeue(&Q);

/*Recover the memory to avoid memory leaks*/

destroyQueue(&Q);

}

/* OUTPUT FROM THE SAMPLE CODE:

Enqueueing three chars, abc

Size = 3

isEmpty = 0

First = a

Traversing the queue: a b c

Dequeueing two chars:

ab

Size = 1

First = c

Dequeueing one char:

c

Size = 0

isEmpty = 1

Attempting to dequeue one char:

ERROR: Queue is empty

*/