passing pointer to structure to a function

Hi Guys,
I am a newbie to c++ programming and I need help with my program. Can anybody help me out? I am trying to pass pointer to a structure to create an object. The program compiles fine but during execution I get the following error:


Debug Assertion Failed!

Program: C:\PROGRAM FILES\.....
File: dbgdel.cpp
Line: 47

Expression: _BLOCK_TYPE_IS_VALID(pHead->nBlockUse)

This is visual studio .net 2003 environment.

Couple of things more: I am just starting out in C++ and any kind of feedback on the logic/design of my program is appreciated. I dont know if passing structures by reference is a good idea, please let me know how to do that. Also please ignore the mess of file input, it is for testing and unrelated (I hope ) to the error. I have an idea that my delete call to destructor is causing the error, but I dont know how and how to fix it. And thanks in advance for your input.

-Sam

I tried searching the forums before posting but could not find anything.

Code:

struct strArray {
	int size;
	int position;
	int *byteArray;
};


class BinaryInputStream {

	protected :	
		strArray *source;
		
	private :
		int i;

	public:
		BinaryInputStream(strArray *source) {
			this->source = source;
			//for (i = 0; i < source->size; i++) {
			i = 0;
			while (i < source->size) {
				cout << "in default constructor " << source->byteArray[i] << "\n";
				i++;
			}

		}
		
		~BinaryInputStream() {
			delete [] source->byteArray;
			delete source;
		}
}

int main(int argc, char **argv) {

	int i = 0, x=0;
	strArray *source;
	strArray src;
	source = & src;

    if ((argc < 2)) {
		cout << "\nMissing arguments\n\n";
		cout << "USAGE : mre inputfilename\n\n";
        return 0;
	} else {
		cout << "Hello World\n The file size is :";		

		ifstream inFile;
		inFile.open(argv[1], ios::binary);
		inFile.seekg(0, ios::end);
		i = inFile.tellg();
		cout <<i << "\n";

		source->byteArray = new int[i];
		if (source->byteArray == NULL) {
			return 0;
		}

		while ((inFile.good()) && (x < i)) {
			source->byteArray[x] = x + 1;
			cout << "Byte " << x << ": " << source->byteArray[x] <<"\n";
			x++;
		}

		inFile.close();

		BinaryInputStream *ptr = new BinaryInputStream(source);
		delete ptr;

	}

	return 0;
}

1)First, I would suggest you use a little more creativity, and not name ANY variables with the same name:

Code:

BinaryInputStream(strArray *source) {
		this->source = source;

How about this:

Code:

BinaryInputStream(strArray* ptr) {
			this->source = ptr;

As it is, it makes it difficult just to talk about your code.

2)You only delete memory that was allocated with new.

Code:

strArray *source;
strArray src;
source = & src;

The variable source is a pointer that was not created using new, so you wouldn't delete it. This is essentially what you are doing:

Code:

#include <iostream>
using namespace std;

int main()
{
	int* source;
	int num = 10;
	source = &num;

	delete source;

	return 0;
}

Try running that program and see what happens.

In addition, you only use "delete []" when you created an array using "new". In otherwords, if you use "new[]", then you use "delete []". If you only used "new", then you only use "delete". Here is an example:

Code:

#include <iostream>
using namespace std;

struct Apple
{
	int size;
	int color;
};

int main()
{
	Apple* ptr1 = new Apple;
	delete ptr1;

	Apple* ptr2 = new Apple[10];  //used new with '[]' somewhere to the right of new
	delete [] ptr2; //..then use delete with '[]'

	return 0;
}

Hi 7stud!

Thanks for your comments. Regarding 1) I completely agree and am thankful for your advice, will follow it. 2) I found that out and fixed it. But 3) was something I had read and learnt but I forgotten about it !! And thanks again!! You guys are awesome!!!

-sam