C / C++ / MFC

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

#if !defined YOURFILENAME<br />
#define YOURFILENAME<br />
<br />
//Declaration of your class<br />
...<br />
...<br />
...<br />
<br />
#endif

#include <process.h>
#include <stdio.h>
#include <stdlib.h>

struct queuelist /* THIS IS 1 NODE IN A LIST - NOT A LIST */
{
	int intData;
	int valid;   /* WHY IS THIS EVEN NEEDED? THIS JUST WASTE MEMORY! */
	struct queuelist* next;
	
};
struct queuelist *head, *tail; /* UNITIALISED GLOBAL VARIABLES */
/* IF YOU WANT THEM TO SELF INTIALISE TO NULL THEN USE STATIC KEYWORD
static struct queuelist *head, *tail;
*/

int AddToQueue(struct queuelist*,int);	/* Prototype does not match function */
/* ...... */
void menu()  /* In C a void argument should be used */
{
	
	int option=0; /* very good */
	struct queuelist* queue; /* ONE CAUSE OF EXCEPTION IN AddToQueue() */
	/* CORRECTION: struct queuelist* queue = NULL; */
	int data;

/* YOU SHOULD BE USING A LOOP STARTING HERE */

	printf("Queue Manipulation Menu\n");
	/* ...... */
	switch(option)
	{
	case 1:
		/* ...... */
		if(AddToQueue(queue,data)==-1) /* Invalid argument: SECONDARY CAUSE OF EXCEPTION */
		/* correction: if(AddToQueue(&queue,data)==-1) */
		/* ...... */
		menu(); /* Recursive call. This is not needed if using a LOOP! */
		/*
		Note: The recursive call would cause a new list to be created
		      basicaly messing up every thing!
		*/
		/* break; SHOULD BE HERE! */		
	/* ...... */
	case 6:
		exit(0);
		/*
		Note: It would be better just to use a break here (to prevent error message below)
		and test if opition == 6 in a loop ( Exp: while( option != 6 ) { do somthing; } ).
		*/
		/* break; SHOULD BE HERE! Not need but good habit. */
	default:
		printf("Invalid Option..\n");
		
	}

/* THIS IS WHERE THE LOOP SHOUD END */
}

void main() /* SHOULD BE int main() IN C - WITH A RETURN STATEMENT AT END OF FUNCTION */
{ /* ...... */ }

int AddToQueue(struct queuelist** q, int data)
{
	struct queuelist** temp; /* YOU DO NOT NEED A POINTER TO A POINTER HERE */
	/* YOU NEED: struct queuelist* temp; */
	/* IF **q THEN THIS SHOULD BE *q = head */
	q = head; /* ASK YOUR SELF: IS head EVER NULL */
	if(q == NULL) /* IF **q THEN THIS SHOULD BE *q = NULL */
	{ /* ...... */ }
	else
	{ /* ...... */ }
/* THERE IS NO RETURN STATEMENT HERE!
THIS FUNCTION JUST RETURNS WHAT EVER HAPPENS TO BE IN THE REGISTER!
YOU DO NOT KNOW WHAT IS RETURNED!
*/
}


void DisplayQueue(struct queuelist* queue)
{
	system("cls");
	queue = head; /* WHY PASS A QUEUE ARGUMENT IF YOU DO NOT USE IT */
	/* ...... */
}

int RemoveFromQueue(struct queuelist* queue)
{
	struct queuelist* prev;
	struct queuelist* second; /* NOT NEEDED */
	queue = head; /* WHY PASS A QUEUE ARGUMENT IF YOU DO NOT USE IT */
	if(queue->valid !=1) /* FORGOT TO CHECK IF queue == NULL */
	{ /* ...... */ }
	else
	{
		queue = head;
		prev = queue;
		queue = queue->next;
		second = queue; /* second NOT USED FOR ANYTHING */
		head = queue;
		printf("Popped off : %d at %x\n",prev->intData, prev->next);
		prev->next = NULL; /* not needed but does not hurt */
		free(prev);
		/* THE ABOVE REDUCED TO 4 LINES
		prev = head;
		head = head->next;
		printf(...);
		free(prev);
		*/
	}
/* THERE IS NO RETURN STATEMENT HERE!
THIS FUNCTION JUST RETURNS WHAT EVER HAPPENS TO BE IN THE REGISTER!
YOU DO NOT KNOW WHAT IS RETURNED!
*/
}

int DeleteQueue(struct queuelist* queue)
{
	struct queuelist* prev;
	queue = head; /* WHY PASS A QUEUE ARGUMENT IF YOU DO NOT USE IT */
	while(queue!=NULL) /* OK */
	{ /* ...... */ }
/* THERE IS NO RETURN STATEMENT HERE!
THIS FUNCTION JUST RETURNS WHAT EVER HAPPENS TO BE IN THE REGISTER!
YOU DO NOT KNOW WHAT IS RETURNED!
*/
}

#include <stdio.h><br />
#include <conio.h><br />
#include <process.h><br />
#include <malloc.h><br />
<br />
struct queuelist<br />
{<br />
	int intData;<br />
	int valid;<br />
	struct queuelist* next;<br />
<br />
};<br />
struct queuelist *head, *tail;<br />
<br />
int AddToQueue(struct queuelist*,int);<br />
int RemoveFromQueue(struct queuelist*);<br />
int DeleteQueue(struct queuelist*);<br />
void DisplayQueue(struct queuelist*);<br />
void menu();<br />
struct queuelist* queue=NULL;<br />
<br />
void menu()<br />
{<br />
<br />
	int option=0;<br />
	<br />
	int data=0;<br />
	printf("Queue Manipulation Menu\n");<br />
	printf("........................\n\n");<br />
	printf("1. Add member to queue.\n");<br />
	printf("2. Extract next member.\n");<br />
	printf("3. Delete whole queue.\n");<br />
	printf("4. Help\n");<br />
	printf("5. Display queue contents.\n");<br />
	printf("6. Quit.\n");<br />
	scanf("%d",&option);<br />
	switch(option)<br />
	{<br />
		case 1:<br />
			queue=head;<br />
			printf("Adding to queue.\n");<br />
			printf("Member: ");<br />
			scanf("%d",&data);<br />
			if(AddToQueue(queue,data)==-1)<br />
				printf("Could not add..\n");<br />
			else<br />
				printf("Added..\n");<br />
			break;<br />
<br />
		case 2:<br />
			system("cls");<br />
			printf("Extract next member.\n");<br />
			RemoveFromQueue(queue);<br />
			break;<br />
<br />
		case 3:<br />
			DeleteQueue(queue);<br />
			break;<br />
<br />
		case 4:<br />
			printf("Under Construction.\n");<br />
		case 5:<br />
			printf("Queue Contents.\n");<br />
			DisplayQueue(queue);<br />
			break;<br />
<br />
		case 6:<br />
			exit(0);<br />
<br />
		default:<br />
			printf("Invalid Option..\n");<br />
<br />
	}<br />
}<br />
<br />
void main()<br />
{<br />
	system("cls");<br />
	while(1)<br />
	menu();<br />
	getch();<br />
<br />
}<br />
<br />
int AddToQueue(struct queuelist* q, int data)<br />
{<br />
	struct queuelist* temp;<br />
	q = head;<br />
	if(q == NULL)<br />
	{<br />
		printf("First member in queue.\n");<br />
		q = (struct queuelist*)malloc(sizeof(struct queuelist));<br />
		if(q == NULL)<br />
		{<br />
			printf("Not enough memory. Stopping...\n");<br />
			return -1;<br />
		}<br />
		else<br />
		{<br />
			q->intData = data;<br />
			q->valid=1;<br />
			q->next=NULL;<br />
			head = q;<br />
			tail = q;<br />
		<br />
		}<br />
<br />
<br />
	}<br />
	else<br />
	{<br />
		q=head;<br />
		while(q->next!=NULL) q = q->next;<br />
<br />
		temp = (struct queuelist*)malloc(sizeof(struct queuelist));<br />
		if(temp == NULL)<br />
		{<br />
			printf("Not enough memory. Quitting...\n");<br />
			return -1;<br />
		}<br />
		else<br />
		{<br />
			temp->intData = data;<br />
			temp->next=NULL;<br />
			q->next = temp;<br />
			q = q->next;<br />
			q->valid = 1;<br />
			tail = q;<br />
<br />
		}<br />
<br />
<br />
	}<br />
<br />
<br />
	return data;<br />
}<br />
<br />
<br />
void DisplayQueue(struct queuelist* queue)<br />
{<br />
	system("cls");<br />
	queue = head;<br />
	if(queue == NULL || queue->valid != 1)<br />
	{<br />
		printf("Empty Queue");<br />
	}<br />
	else<br />
	{<br />
	while(queue != NULL)<br />
	{<br />
		printf("||%d|%x||->",queue->intData,queue->next);<br />
		queue = queue->next;<br />
	}<br />
<br />
	}<br />
	printf("\n");<br />
<br />
}<br />
<br />
int RemoveFromQueue(struct queuelist* queue)<br />
{<br />
<br />
	struct queuelist* prev;<br />
	struct queuelist* second;<br />
	queue = head;<br />
	if(queue->valid !=1 || queue==NULL)<br />
	{<br />
		printf("Queue Exhausted. No members.\n");<br />
		return -1;<br />
	}<br />
	else<br />
	{<br />
		queue = head;<br />
		prev = queue;<br />
		queue = queue->next;<br />
		second = queue;<br />
		head = queue;<br />
		printf("Popped off : %d at %x\n",prev->intData, prev->next);<br />
		prev->next = NULL;<br />
		free(prev);<br />
	}<br />
<br />
	return prev->intData;<br />
<br />
}<br />
int DeleteQueue(struct queuelist* queue)<br />
{<br />
	struct queuelist* prev;<br />
	queue = head;<br />
	if(queue == NULL)<br />
		return -1;<br />
	while(queue!=NULL)<br />
	{<br />
		prev = queue;<br />
		queue = queue->next;<br />
		queue->valid=0;<br />
		free(prev);<br />
	}<br />
<br />
	return 1;<br />
}

/* A simple global list in C */

/* A simple list node */
typedef struct tagNode
{
    struct tagNode* pNext;
    int intData;
} NODE; /* Using typedef to avoid need to type 'struct tagNode' */

/* Global list head */
static NODE* g_pHead; /* 'static' makes it local global and = NULL */

/* Function prototypes */
int AddNode(int intData);    /* Add new data node to end of list */
int DisplayList();           /* Display all data in list */
int DeleteNode();            /* Remove and delete node from start of list */
void DeleteAll();            /* Delete all node in list */

// A Simple linked list class in C++
class CIntList // class defults to private
{
// Private data and declarations
    struct NODE
    {
        struct NODE* pNext;
        int intData;
    };
    NODE* m_pHead; // Pointer to list head

// Public interface
public:
    int AddNode(int intData);    // Add new data node to end of list
    int DisplayList();           // Display all data in list
    int DeleteNode();            // Remove and delete node from start of list
    void DeleteAll();            // Delete all node in list

// Constructor and Destructor
    CIntList() : m_pHead(NULL) {} // Initialize head point to NULL
    ~CIntList() { DeleteAll(); }  // Make sure list if freed when destoyed
};

  CButton *But=(CButton*)this->GetDlgItem(ID_BUTTON1);<br />
   <br />
if(But)<br />
{<br />
 But->EnableWindow(FALSE);<br />
}