getting bad_alloc from new

[wasabi]

I'm running a program and am getting a bad_alloc exception from new. The problem is not that I've run out of memory, my program isn't that resource-intensive.

The relevant code is the following:

bool NFault::Generate(fstream& f, NColor& fillColor, NColor& wireframeColor)
{
	//...
	float* normal = NULL;
	try{normal = new float[3*NumVertexes]; //will hold normals of each vertex
	}catch(std::exception& e) { cout << e.what();}
	for(unsigned int i=0;i<3*NumVertexes;i++)
		normal[i]=0.f; //normals start at 0.f
	for(unsigned int i=0;i<NumIndexes;i+=3)
	{
		NVertexGeometry vx1=Geometry[Index[i]];
		NVertexGeometry vx2=Geometry[Index[i+1]];
		NVertexGeometry vx3=Geometry[Index[i+2]];
		MyNVector v1(vx1,vx2);
		MyNVector v2(vx1,vx3);

		MyNVector _normal = v1.CrossProduct(v2);

		for(int j=0;j<3;j++)
		{
			normal[3*Index[i+j]]+=_normal.x;
			normal[3*Index[i+j]+1]+=_normal.y;
			normal[3*Index[i+j]+2]+=_normal.z;
		}
	}
	for(unsigned int i=0;i<NumVertexes;i++)
		Geometry[i].SetNormal(normal[3*i],normal[3*i+1],normal[3*i+2]); 
	delete[] normal;
	return true;

This function is called twice (by two different objects). It goes through the first time just fine, but then throws an exception at line 5 the second time.

Any hints regarding what's going on?

[Disch]

what does NumVertexes equal when the exception is thrown? If it's <= 0 then that would be a problem.

[wasabi]

It equals 364 the first time and 382 the second. Yeah, I should've mentioned that, I feared it might've been set to 0 so I'd already checked that.

[Disch]

Strange indeed. I don't see anything here that could be causing it. The only thing I can think of would be heap corruption, but that's kind of a catch-all.

Maybe try using a vector instead. If the problem goes away then it's almost certainly heap corruption.

bool NFault::Generate(fstream& f, NColor& fillColor, NColor& wireframeColor)
{
	//...
	std::vector<float> normal(3 * NumVertexes, 0);

	for(unsigned int i=0;i<NumIndexes;i+=3)
	{
		NVertexGeometry vx1=Geometry[Index[i]];
		NVertexGeometry vx2=Geometry[Index[i+1]];
		NVertexGeometry vx3=Geometry[Index[i+2]];
		MyNVector v1(vx1,vx2);
		MyNVector v2(vx1,vx3);

		MyNVector _normal = v1.CrossProduct(v2);

		for(int j=0;j<3;j++)
		{
			normal[3*Index[i+j]]+=_normal.x;
			normal[3*Index[i+j]+1]+=_normal.y;
			normal[3*Index[i+j]+2]+=_normal.z;
		}
	}
	for(unsigned int i=0;i<NumVertexes;i++)
		Geometry[i].SetNormal(normal[3*i],normal[3*i+1],normal[3*i+2]); 
	//delete[] normal;
	return true;

[wasabi]

As I said, the function is run twice, back to back. The first time it works just fine, it's just the second time that it crashes. Does that indicate anything?

[Disch]

The only thing it indicates to me is heap corruption.

Are you sure you're not stepping out of bounds anywhere? I can't tell from the code you posted, and the nasty thing with heap corruption is that the problem could be anywhere in the program.

The only thing I see that's a little fishy is the 'Index' array:

NVertexGeometry vx1=Geometry[Index[i]]; // isn't 'i' the index? What do you need Index for?

[wasabi]

Maybe try using a vector instead. If the problem goes away then it's almost certainly heap corruption.

Sorry for the delay, but I have just implemented it using a vector and it still gives an error. However, couldn't the problem still be heap corruption? Isn't a vector basically a convoluted array? Wouldn't it be just as vulnerable to failed allocations due to heap corruption?

[wasabi]

Just found my error. In a previous part of the function, I had a static variable acting as an iterator. I thought that since different instances called the function each time, it would be a new static variable that was created for each instance. I was wrong. Thus, when the second instance called the function, the iterator began at 364.

I knew static members were shared between different instances, but I thought static variables declared inside non-static functions were instantiated. My mistake.