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bad pointer

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My pointer gets changed some strange way, but I don't know why.

// --- Code from my 3DS loader in static lib
CLight *CFile::getLight(int i)
	if( i >= (int)m_LightList.size() )
		return NULL;

	CLight *pLight = m_LightList;

        // Print out men address here
	cout << "npos: " << &pLight->Name << endl;
	cout << "lpos: " << &pLight->m_Position << endl;

        // return pointer to light
	return pLight;

// --- code from my .Exe file that use the static lib.
CLight *pLight = pFile->getLight(0);
cout << "name pos: " << &pLight->Name << endl;
cout << "light pos: " << &pLight->m_Position << endl;

// --- Light class 
class CLight {
 char Name[21];

 CVertex3f m_Position;

 // Function to read data from 3DS file.
 void readData(...);

So my problem is that I don't get the correct position on my light, when calling the pFile->getLight(0); the function prints the memory adresses for both members of the light (name and position) and so it does just after retriving the light. giving bad result, the pLight->Name has the same memory address in both cases BUT not the m_Position so WHY? there is NOTHING that change the lights position.

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Your memory is simply overwritten by some nasty code. =)

The easiest way to solve it is to use the debugger!
Try setting a breakpoint on the memory address that change value. Or step through the code and see what happens on every line.

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Once more (with feeling?), what does your debugger tell you?

Original post by erissian
Most immediately I notice that your function returns CLight, when it should return CLight*.

No, he's correctly returning a CLight *.


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The debugger gave me the same result as my added cout-lines, altough I solved the problem late last night. My static Lib3DS.lib file was compiled using the struct member alignment set to one byte and the .exe file was compiled with the struct member alignment set to default (Using VC++ 2005 Express).

So now my question is, Can I some way change the alignment of the structs that need this in my code? this way the user of the 3DS library doesn't need to compile his/hers code using 1 byte alignment of structures.

Edit: I found the '#pragma pack' command to change the alignment of a struct like this:

#pragma pack(push, 1)
// Some code with alignment 1

#pragma pack(pop)
// continue with code at default alignment

[Edited by - McZ on December 18, 2005 2:23:26 PM]

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