queue/queuedemo.h ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

/*********************************************************************
*  FILE:	queuedemo.h
*  AUTHOR:	Mike McCarthy
*  HARVARD ID:	00161118
*  DATE:	June 2003
*  PURPOSE:	header file for queuedemo.c
*********************************************************************/
#define BUFSIZE 512
#define SMBUFSIZE 255

FILE* setup(char*);
void fatal(char*, char*);

[END: queue/queuedemo.h]========================================================
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queue/queuedemo.c ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

/*********************************************************************
*  FILE:	queuedemo.c
*  AUTHOR:	Mike McCarthy
*  HARVARD ID:	00161118
*  DATE:	June 2003
*  PURPOSE:	Demo of dynamic queue data structure. 
*
*  NOTES:	Uses a simple struct containing a char* and int.
*
*		Reads from filename supplied as command line arg.
*
*  USAGE:	At the command line, type: queuedemo data
*
*********************************************************************/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "queuedemo.h"
#include "queue.h"

int main(int argc, char* argv[])
{
	char buf[BUFSIZE], string[SMBUFSIZE], value[SMBUFSIZE];
	node* front_node;
	FILE* fp = NULL;

	if(argc != 2)
		fatal("incorrect number of arguments", "");

	fp = setup(argv[1]);

	printf("\n");
	while(fgets(buf, BUFSIZE, fp) != NULL){
		if(sscanf(buf, "%s%s", string, value) != 2)
			fatal("file is corrupt", "");
		if(enqueue(string, value) != OK)
			fatal("memory failure", "");
	}

	printf("\n");
	while((front_node = dequeue()) != NULL){
		printf("dequeuing: %s %d\n", front_node->str, front_node->num);
		delete_node(front_node);
		show_queue();
	}

	fclose(fp);
	printf("\n");
	return 0;
}

/********************************************************************/

FILE* setup(char* fname)
{
	FILE* fp;
	fp = fopen(fname, "r");
	if(!fp){
		perror(fname);
		exit(1);
	}
	init_queue();
	return fp;
}

/********************************************************************/

void fatal(char* s1, char* s2)
{
	fprintf(stderr, "Error: %s %s\n", s1, s2);
	exit(1);
}

/********************************************************************/

[END: queue/queuedemo.c]========================================================
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queue/queue.h ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

/*********************************************************************
*  FILE:	queue.h
*  AUTHOR:	Mike McCarthy
*  HARVARD ID:	00161118
*  DATE:	June 2003
*  PURPOSE:	header file for queue.c
*********************************************************************/
#define NOT_OK 0
#define OK 1

struct node{
	char* str;
	int num;
	struct node* next;
};
typedef struct node node;

void init_queue();
int enqueue(char*, char*);
node* dequeue();
node* get_node(char*);
void delete_node(node*);
void show_queue();

[END: queue/queue.h]============================================================
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queue/queue.c ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

/*********************************************************************
*  FILE:	queue.c
*  AUTHOR:	Mike McCarthy
*  HARVARD ID:	00161118
*  DATE:	June 2003
*  PURPOSE:	Implentation file for queue functions
*********************************************************************/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "queuedemo.h"
#include "queue.h"

static node* front;

/********************************************************************/

void init_queue()
{
	front = NULL;
}

/********************************************************************/

int enqueue(char* s1, char* s2)
{
	node* new_node, *temp, *tail;
	new_node = get_node(s1);
	if(new_node == NULL)
		return NOT_OK;

	strcpy(new_node->str, s1);
	new_node->num = atoi(s2);
	printf("enqueuing: %s %d\n", new_node->str, new_node->num);
	if(front == NULL){
		front = new_node;
		new_node->next = NULL;
	}
	else{
		temp = front;
		while(temp != NULL){
			tail = temp;
			temp = temp->next;
		}
		tail->next = new_node;
		new_node->next = NULL;
	}
	show_queue();
	return OK;
}

/********************************************************************/

node* get_node(char* str)
{
	node* new_node = malloc(sizeof(node));
	if(!new_node)
		return NULL;
	new_node->str = malloc(strlen(str) + 1);
	if(!new_node->str)
		return NULL;
	return new_node;
}

/********************************************************************/

node* dequeue()
{
	node* dequeued_front;
	if(front == NULL)
		return NULL;
	dequeued_front = front;
	front = front->next;
	return dequeued_front;
}

/********************************************************************/

void delete_node(node* node_to_delete)
{
	free(node_to_delete->str);
	free(node_to_delete);
}

/********************************************************************/

void show_queue()
{
	node* temp;
	temp = front;
	printf("\tQUEUE CONTAINS: ");
	while(temp != NULL){
		printf("%s ", temp->str);
		temp = temp->next;
	}
	printf("\n");
}

/********************************************************************/

[END: queue/queue.c]============================================================
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