Dev-Cpp "Access violation"!? Why?

gamescoper · Post by **gamescoper** » Wed Aug 20, 2008 5:00 pm

I was debugging my code as it wasnt working and devcpp kept giving me this error "An Access Violation (Segmentation Fault) raised in your program." I know it has something to do with a pointer being corrupted or something but I am not greatly well versed in C++ so i am quite lost.

The debugger pointed to this line being the "violater":

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    io::IXMLReader* xml = device->getFileSystem()->createXMLReader("settings.xml");

I have the source code here:

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#include "include/irrlicht.h"
#include "include/irrxml.h"
#include <string>
using namespace irr;
using namespace core;
using namespace scene;
using namespace video;
using namespace io;
using namespace gui;

#ifdef _IRR_WINDOWS_
#pragma comment(lib, "Irrlicht.lib")
#endif
IrrlichtDevice *device = 0;
core::stringw width;
core::stringw height;
core::stringw name;
core::stringw slogan;
s32 cnt = 0;
IGUIListBox* listbox = 0;
class MyEventReceiver : public IEventReceiver
{
public:
	virtual bool OnEvent(const SEvent& event)
	{
		if (event.EventType == EET_GUI_EVENT)
		{
			s32 id = event.GUIEvent.Caller->getID();
			IGUIEnvironment* guienv = device->getGUIEnvironment();
			switch(event.GUIEvent.EventType)
{
    case EGET_BUTTON_CLICKED:

				if (id == 1)
				{
					guienv->clear();
					guienv->addButton(rect<s32>(88, 64, 304, 96), 0, 5, L"Back");
                    guienv->addStaticText(L"Story mode in develpoment", rect<s32>(88, 16, 304, 36), false, false, 0, -1);
					return true;
				}
                if (id == 2)
                {
                       guienv->clear();
                       guienv->addButton(rect<s32>(88, 64, 304, 96), 0, 5, L"Back");
                       guienv->addStaticText(L"Multiplayer mode in develpoment", rect<s32>(88, 16, 304, 36), false, false, 0, 5);
                }
                if (id == 5)
                {
                       guienv->clear();
                       guienv->addButton(rect<s32>(88, 200, 304, 240), 0, 4, L"Exit");
	                   guienv->addButton(rect<s32>(88, 152, 304, 192), 0, 3, L"Options");
                       guienv->addButton(rect<s32>(88, 104, 304, 144), 0, 2, L"Multiplayer");
                       guienv->addButton(rect<s32>(88, 56, 304, 96), 0, 1, L"Story Mode");
                       guienv->addStaticText(L"Game menu", rect<s32>(88, 16, 304, 36), false, false, 0, -1);
                }
                if (id == 4)
                {
                       device->closeDevice();
                }
                if (id == 3)
                {
                       guienv->clear();
                       
                }                     


}
}
return false;}
};

int main()
{

//XML settisdaadasdngs reader
	// read configuration from xml file
    io::IXMLReader* xml = device->getFileSystem()->createXMLReader("settings.xml");
	while(xml && xml->read())
	{
		switch(xml->getNodeType())
		{
		case io::EXN_TEXT:
			// in this xml file, the only text which occurs is the messageText
			//MessageText = xml->getNodeData();
			break;
		case EXN_ELEMENT:
			{
				if (core::stringw("windowsize") == xml->getNodeName())
                   {
					width = xml->getAttributeValue(L"width");
					height = xml->getAttributeValue(L"width");
                   }
				else
				if (core::stringw("userdata") == xml->getNodeName())
				   	{
                    name = xml->getAttributeValue(L"name");
					slogan = xml->getAttributeValue(L"slogan");
                    }
			}
			break;
		}
	}
	if (xml)
		xml->drop(); // don't forget to delete the xml reader 


//End XML settings reader

    MyEventReceiver receiver;
    device = createDevice( video::EDT_SOFTWARE, dimension2d<s32>(640, 480), 32, true, false, false, &receiver);
    device->setWindowCaption(L"Window");
    IVideoDriver* driver = device->getVideoDriver();
	ISceneManager* smgr = device->getSceneManager();
	IGUIEnvironment* guienv = device->getGUIEnvironment();
	guienv->addButton(rect<s32>(88, 200, 304, 240), 0, 4, L"Exit");
	guienv->addButton(rect<s32>(88, 152, 304, 192), 0, 3, L"Options");
    guienv->addButton(rect<s32>(88, 104, 304, 144), 0, 2, L"Multiplayer");
    guienv->addButton(rect<s32>(88, 56, 304, 96), 0, 1, L"Story Mode");
    guienv->addStaticText(L"WW2D", rect<s32>(88, 10, 304, 36), false, false, 0, -1);
    guienv->addStaticText(L"Game menu", rect<s32>(88, 16, 304, 36), false, false, 0, -1);
/*IGUIImage *img501 = guienv->addImage(rect<s32>(168, 40, 268, 65), 0, -1, L"");
img501->setImage(guienv->getVideoDriver()->getTexture("C:/Documents and Settings/Sameh/My Documents/My Pictures/button.png"));*/



    while(device->run())
	{
		driver->beginScene(true, true, SColor(255,100,101,140));
		smgr->drawAll();
		guienv->drawAll();
		driver->endScene();
    }
device->drop();

}

rogerborg · Post by **rogerborg** » Wed Aug 20, 2008 5:41 pm

gamescoper wrote:

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IrrlichtDevice *device = 0;
/...
    io::IXMLReader* xml = device->getFileSystem()->createXMLReader("settings.xml");
/...
    device = createDevice( video::EDT_SOFTWARE, dimension2d<s32>(640, 480), 32, true, false, false, &receiver);
}

You're using 'device' before you've set it to anything valid. You'll want to do createDevice() as soon as possible, so that device is valid.

Yustme · Post by **Yustme** » Wed Aug 20, 2008 5:43 pm

Hi,

You are using "device" right at the beginning (somewhere) in your main() function.

It isn't initialized. You initialize it under the while(xml && xml->read()).

You can fix it by putting (at least) the device initialization right above the xml code block like this:

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int main()
{
MyEventReceiver receiver;
    device = createDevice( video::EDT_SOFTWARE, dimension2d<s32>(640, 480), 32, true, false, false, &receiver);

//XML settisdaadasdngs reader
	// read configuration from xml file
    io::IXMLReader* xml = device->getFileSystem()->createXMLReader("settings.xml");
	while(xml && xml->read())
	{
		switch(xml->getNodeType())
		{
		case io::EXN_TEXT:
			// in this xml file, the only text which occurs is the messageText
			//MessageText = xml->getNodeData();
			break;
		case EXN_ELEMENT:
			{
				if (core::stringw("windowsize") == xml->getNodeName())
                   {
					width = xml->getAttributeValue(L"width");
					height = xml->getAttributeValue(L"width");
                   }
				else
				if (core::stringw("userdata") == xml->getNodeName())
				   	{
                    name = xml->getAttributeValue(L"name");
					slogan = xml->getAttributeValue(L"slogan");
                    }
			}
			break;
		}
	}
	if (xml)
		xml->drop(); // don't forget to delete the xml reader 
}

If you didn't understood it, ask your questions

gamescoper · Post by **gamescoper** » Thu Aug 21, 2008 9:09 am

thanks for your but i want the window size to be affected by the settings in the xml file, if the device is initialised before the xml file is read can i re-initialise the device

randomMesh · Post by **randomMesh** » Thu Aug 21, 2008 9:15 am

gamescoper wrote:thanks for your but i want the window size to be affected by the settings in the xml file, if the device is initialised before the xml file is read can i re-initialise the device

Use the NullDevice for reading, then drop() it and create another device.

gamescoper · Post by **gamescoper** » Thu Aug 21, 2008 9:45 am

i edited this line so the second device is made with the variables from the xml file:

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    device = createDevice( video::EDT_SOFTWARE, dimension2d<s32>(width,height), 32, true, false, false, 0);

but now the compiler gives me these errors

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main.cpp: In function `int main()':
main.cpp:111: error: no matching function for call to `irr::core::dimension2d<irr::s32>::dimension2d(irr::core::stringw&, irr::core::stringw&)'
include/dimension2d.h:18: note: candidates are: irr::core::dimension2d<irr::s32>::dimension2d(const irr::core::dimension2d<irr::s32>&)
include/dimension2d.h:24: note:                 irr::core::dimension2d<T>::dimension2d(const T&, const T&) [with T = irr::s32]
include/dimension2d.h:21: note:                 irr::core::dimension2d<T>::dimension2d() [with T = irr::s32]

make.exe: *** [main.o] Error 1

Execution terminated

randomMesh · Post by **randomMesh** » Thu Aug 21, 2008 9:50 am

gamescoper wrote:error: no matching function for call to `irr::core::dimension2d<irr::s32>::dimension2d(irr::core::stringw&, irr::core::stringw&)'

width and height have to be int, not stringw.

gamescoper · Post by **gamescoper** » Thu Aug 21, 2008 10:02 am

ahh thanks

but the variables have to be set as a stringw as the xml reader doesnt seem to output as integers

Dark_Kilauea · Post by **Dark_Kilauea** » Thu Aug 21, 2008 1:26 pm

Perhaps you should read the XML reader documentation?

getAttributeValueAsInt() is probably what you're looking for.

gamescoper · Post by **gamescoper** » Thu Aug 21, 2008 5:49 pm

i would look through the docs except i find it hard to englishly understand it and i dont know where to look for what since it just shows me the class name for c++ but doesnt categorise them like "XML Reader" or "3D Rendering" etc.

I personally think that putting them in nice categories would sharply reduce the questions in this forum but i guess its nico's choice or whoever runs this forum/documentation

Oh btw thanks

wyrmmage · Post by **wyrmmage** » Thu Aug 21, 2008 9:16 pm

Just so you know, this doesn't have anything to do with Dev-Cpp, it's just a problem with the code

-wyrmmage

Irrlicht Engine

Dev-Cpp "Access violation"!? Why?

Dev-Cpp "Access violation"!? Why?

Re: Dev-Cpp "Access violation"!? Why?

Re: Dev-Cpp "Access violation"!? Why?