Why Does My Program Crash?

**Grantyt3** · 09-29-2005

I finally got working on my snake game again. Right now, i've only gotten it to work to the point where you can move one piece of the snake around. Now i'm trying to get it to seem like a whole snake is moving. The way I'm doing it is that I'm deleting the back end of the snake and adding another one at the head. This probably isn't the best way to do it, so if you could tell me what would be a better way, then that would be good. But right now, the game is crashing right as it starts. Here's the code:

Code:

//Includes
#include <allegro.h>
#include<iostream>
#include<string>
#include <stdlib.h>
#include <stdlib.h> 
#include <cstdlib>
#include <time.h>
#include <vector>
#include <complex>
#include <math.h>
#include <cmath>

using namespace std;

//Graphics
BITMAP *snakeimg = NULL;
BITMAP *buffer = NULL;

//Sounds

//Variables
float x,y;
float dir = 45;
float dx = sin(dir);
float dy = cos(dir);
#define PI 3.14159265
int maxsize = 3;


//Structs
struct snake {
	int x;
	int y;
};

struct fruit {
	int x;
	int y;
};

//Vectors
vector<snake> snakes(0);

//Functions
void UpdateSnake();
void TestKeys();

int main(int argc, char argv[1])
{
	
	allegro_init();
	install_keyboard();
	set_color_depth(24);
	set_gfx_mode(GFX_AUTODETECT_WINDOWED,400,400,0,0);

	//BITMAPS
	snakeimg = load_bitmap("Snake.bmp",NULL);
	buffer = create_bitmap(400,400);

	while(!key[KEY_ESC])
	{
	clear_bitmap(buffer);
	TestKeys();
	UpdateSnake();
	draw_sprite(screen,buffer,0,0);
	}

	allegro_exit();
	return 0;

	//Cleanup
	for(int i = 0;i < snakes.size(); i++);
	{
		snakes.erase(snakes.begin()+i);
	}
	destroy_bitmap(snakeimg);
	destroy_bitmap(buffer);
}

	
END_OF_MAIN();

void UpdateSnake()
{
	dx = sin(dir*PI/180);
	dy = cos(dir*PI/180);
	x = x + dx/5;
	y = y + dy/5;

	snake w;
	w.x = x;
	w.y = y;
	snakes.push_back(w);

	if(snakes.size() > maxsize)
	{
		snakes.erase(snakes.begin()+snakes.size());
	}

	for(int i = 0; i < snakes.size(); i++)
	{
		draw_sprite(buffer,snakeimg,snakes[i].x,snakes[i].y);
	}
}

void TestKeys()
{
	if(key[KEY_LEFT])
	{
		dir = dir + .4; 
	}
	else if(key[KEY_RIGHT])
	{
		dir = dir - .4;
	}
}

**C+noob** · 09-29-2005

you need to include windows.h and use a callback procedure for the key messages.

in other words learn some win32 programming first....

www.winprog.org is GREAT for beginners www.functionx.com is also ok and http://code.glowdot.com is AWESOME for advanced win32, need good C++ skills though

**C+noob** · 09-29-2005

need help? PM ME

**Grantyt3** · 09-29-2005

But it worked fine without including window.h before. I havn't added anything that I havn't done before without it.

**C+noob** · 09-29-2005

oh, my bad your using allegro. sorry to bursty your bubble allegro is the easy awy out and can get pretty glitchy i stand buy what i said ditch allegro and go with good ol' win32 and pure C++ also why do you include cmath and math.h u shud only want math.h cmath is old version of math.h

**C+noob** · 09-29-2005

and dont go usin any of that MFC crap lol

edit: these are just suggestions, its your choice really just tryin to help out

**Grantyt3** · 09-29-2005

I guess I don't know what win32 is... I didn't know you could do graphics with it. But for this project I'm going to stick with allegro, unless it gets reaaally buggy. I found that the problem is in this block :

Code:

if(snakes.size() > maxsize)
{
   snakes.erase(snakes.begin()+snakes.size());
}

**C+noob** · 09-29-2005

great btw win32 isnt consoles its like windows and such.like internet explorer its win32 programmed win32 is the art of creating windows resources button edits etc.

make a windows project and compile this:

Code:

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, WPARAM wParam, LPARAM lParam)
{
    MessageBox("my Message Box", "Title of my message box", MB_OK | MB_ICONERROR);
}

**C+noob** · 09-29-2005

make sure to add #include <windows.h> at the top

**Grantyt3** · 09-29-2005

IT gives me the error unexpected end of file while looking for precompiled header directive.

**C+noob** · 09-29-2005

i hate typing callbacks ill give u alot of code to compile mmk *gawd* make sure you make a windows project

Code:

// basic window creation learn basic win32 @ www.winprog.org
#include <windows.h>

/*  Declare Windows procedure  */
LRESULT CALLBACK WindowProcedure (HWND, UINT, WPARAM, LPARAM);

/*  Make the class name into a global variable  */
char szClassName[ ] = "WindowsApp";

int WINAPI WinMain (HINSTANCE hThisInstance,
                    HINSTANCE hPrevInstance,
                    LPSTR lpszArgument,
                    int nFunsterStil)

{
    HWND hwnd;               /* This is the handle for our window */
    MSG messages;            /* Here messages to the application are saved */
    WNDCLASSEX wincl;        /* Data structure for the windowclass */

    /* The Window structure */
    wincl.hInstance = hThisInstance;
    wincl.lpszClassName = szClassName;
    wincl.lpfnWndProc = WindowProcedure;      /* This function is called by windows */
    wincl.style = CS_DBLCLKS;                 /* Catch double-clicks */
    wincl.cbSize = sizeof (WNDCLASSEX);

    /* Use default icon and mouse-pointer */
    wincl.hIcon = LoadIcon (NULL, IDI_APPLICATION);
    wincl.hIconSm = LoadIcon (NULL, IDI_APPLICATION);
    wincl.hCursor = LoadCursor (NULL, IDC_ARROW);
    wincl.lpszMenuName = NULL;                 /* No menu */
    wincl.cbClsExtra = 0;                      /* No extra bytes after the window class */
    wincl.cbWndExtra = 0;                      /* structure or the window instance */
    /* Use Windows's default color as the background of the window */
    wincl.hbrBackground = (HBRUSH) COLOR_BACKGROUND;

    /* Register the window class, and if it fails quit the program */
    if (!RegisterClassEx (&wincl))
        return 0;

    /* The class is registered, let's create the program*/
    hwnd = CreateWindowEx (
           0,                   /* Extended possibilites for variation */
           szClassName,         /* Classname */
           "Windows App",       /* Title Text */
           WS_OVERLAPPEDWINDOW, /* default window */
           CW_USEDEFAULT,       /* Windows decides the position */
           CW_USEDEFAULT,       /* where the window ends up on the screen */
           544,                 /* The programs width */
           375,                 /* and height in pixels */
           HWND_DESKTOP,        /* The window is a child-window to desktop */
           NULL,                /* No menu */
           hThisInstance,       /* Program Instance handler */
           NULL                 /* No Window Creation data */
           );

    /* Make the window visible on the screen */
    ShowWindow (hwnd, nFunsterStil);
    UpdateWindow(hwnd);

    /* Run the message loop. It will run until GetMessage() returns 0 */
    while (GetMessage (&messages, NULL, 0, 0))
    {
        /* Translate virtual-key messages into character messages */
        TranslateMessage(&messages);
        /* Send message to WindowProcedure */
        DispatchMessage(&messages);
    }

    /* The program return-value is 0 - The value that PostQuitMessage() gave */
    return messages.wParam;
}


/*  This function is called by the Windows function DispatchMessage()  */

LRESULT CALLBACK WindowProcedure (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch (message)                  /* handle the messages */
    {
        case WM_DESTROY:
            PostQuitMessage (0);       /* send a WM_QUIT to the message queue */
            break;
        default:                      /* for messages that we don't deal with */
            return DefWindowProc (hwnd, message, wParam, lParam);
    }

    return 0;
}

make sure you have a WINDOWS PROJECT

Note: this may seem like alot of code... it is. but if u wanna add edit boxes and other stuff like that you need to add very little code. (Win32 Template made by Dev C++)

**Ancient Dragon** · 09-29-2005

Originally Posted by Grantyt3

IT gives me the error unexpected end of file while looking for precompiled header directive.

if you are using VC++ 6.0 or .NET compiler then either turn precompiled headers off or add #include "stdafx.h" at the top of the *.cpp file. You HAVE to turn them off for *.c files.

**C+noob** · 09-29-2005

true but the error was my fault.

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, WPARAM wParam, LPARAM lParam)

WPARAM and LPARAM dont belong in there i was thinking callbacks replaace tht with:

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpszArgument, int nFunsterStil)

**Tonto** · 09-29-2005

C+noob: stop babbling with these off-topic win32 comments. It's retarded. You're comment about Allegro was entirely unfounded and your just spitting out BS and making a fool of yourself. As to the original question:

Code:

	return 0;

	//Cleanup
	for(int i = 0;i < snakes.size(); i++);
	{
		snakes.erase(snakes.begin()+i);
	}
	destroy_bitmap(snakeimg);
	destroy_bitmap(buffer);

I don't believe that cleanup is ever reached. You return 0 before you get there.
The real problem, however, as you had mentioned

Code:

snakes.erase(snakes.begin()+snakes.size());

I think is that, snakes.begin() returns a pointer to the first element of the vector, which you add snakes.size() to (which returns 1, 2, 3, whatev) and it crashes.

**C+noob** · 09-29-2005

no need to flame and yea allegro is a piece of ........

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