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Heap Corruption in overloaded operators

BAC Sun (14)
I've been building a Big Integer calculator. If I use a member function to multiply the BigInts together, then everything works fine. When I move my multiply function into an overloaded * or *= function, I start getting heap corruptions. Can anyone help me find where the problem lies? I did the same thing with my add function and have no problems there, just with the multiplication.

Here is the add multiplication functions I was using:
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BigInteger BigInteger::add(const BigInteger& rhs)
{
	BigInteger result;
	unsigned int length = (this->m_digitCount > rhs.m_digitCount) ? this->m_digitCount : rhs.m_digitCount;

	int carry = 0;
	for (unsigned int digit = 0; digit < length; digit++)
	{
		int v1 = this->getDigit(digit);
		int v2 = rhs.getDigit(digit);
		int sum = v1 + v2 + carry;
		int single = sum % 10;
		carry = ((sum - single) > 0) ? (sum - single) / 10 : 0;

		result.setDigit(digit, single);
	}
	if (carry > 0)
	{
		result.setDigit(length, carry);
	}

	return result;
}

BigInteger BigInteger::multiply(const BigInteger& rhs)
{
	BigInteger result;
	const BigInteger& b = (this->m_digitCount < rhs.m_digitCount) ? *this : rhs;
	const BigInteger& t = (this->m_digitCount < rhs.m_digitCount) ? rhs : *this;

	for (unsigned int bDigit = 0; bDigit < b.m_digitCount; bDigit++)
	{
		BigInteger temp(0);
		int v1 = b.getDigit(bDigit);
		int carry = 0;
		for (unsigned int tDigit = 0; tDigit < t.m_digitCount; tDigit++)
		{
			int v2 = t.getDigit(tDigit);
			int sum = v1 * v2 + carry;
			int single = sum % 10;
			carry = ((sum - single) > 0) ? (sum - single) / 10 : 0;

			temp.setDigit(bDigit + tDigit, single);
		}
		if (carry > 0)
		{
			temp.setDigit(bDigit + t.m_digitCount, carry);
		}

		BigInteger temp2 = result.add(temp);
		result = temp2;

	}

	return result;
}


From BigInteger.hpp
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#ifndef _BIGINTEGER_HPP_
#define _BIGINTEGER_HPP_

#include <cstdint>
#include <iostream>
#include <string>

class TestCases;

class BigInteger
{
public:
	BigInteger()
	{
		m_sizeReserved = 4;
		m_digitCount = 0;
		m_number = new uint8_t[m_sizeReserved];
	}
	BigInteger(int number) 
	{
		int inbound = number;
		m_digitCount = 1;
		for (unsigned int i = number; i > 1; i /= 10)
		{
			++m_digitCount;
		}
		m_sizeReserved = 4;
		while (m_sizeReserved <= m_digitCount)
		{
			m_sizeReserved *= 2;
		}
		m_number = new uint8_t[m_sizeReserved];
		for (unsigned int i = 0; i < m_digitCount; ++i)
		{
			uint8_t input = inbound % 10;
			setDigit(i, input);
			inbound /= 10;
		}
	}
	BigInteger(std::string number)
	{
		m_digitCount = number.size();
		m_sizeReserved = 4;
		while (m_sizeReserved <= m_digitCount)
		{
			m_sizeReserved *= 2;
		}
		m_number = new uint8_t[m_sizeReserved];
		for (unsigned int i = 0; i < m_digitCount; ++i)
		{
			unsigned int input = (number[m_digitCount - i - 1] - '0');
			setDigit(i, input);
		}
	}
	BigInteger(const BigInteger& rOther)
	{
		m_sizeReserved = rOther.m_sizeReserved;
		m_digitCount = rOther.m_digitCount;
		m_number = new uint8_t[m_sizeReserved];
		for (unsigned int  i = 0; i < m_digitCount; ++i)
		{
			setDigit(i, rOther.m_number[i]);
		}
	}

	//overridden opperators
	BigInteger operator=(const BigInteger& rOther);
	BigInteger operator+(const BigInteger& rhs);
	BigInteger operator+(const unsigned int& rhs);
	BigInteger operator+=(const BigInteger& rhs);
	BigInteger operator++(int);
	BigInteger operator*(const BigInteger& rhs);
	BigInteger operator*=(const BigInteger& rhs);
	operator double();
	bool operator<=(const BigInteger& rhs);
	bool operator==(const BigInteger& rhs);
	friend std::ostream& operator<<(std::ostream& os, const BigInteger rhs);
	
	friend TestCases; // TODO Have students do this first thing

	~BigInteger()
	{
		for (unsigned int i = 0; i < m_sizeReserved; ++i)
		{
			m_number[i] = NULL;
		}
		m_digitCount = NULL;
		m_sizeReserved = NULL;
		delete[] m_number;
	}

private:
	std::uint8_t* m_number;		// Internal representation of the number.
	unsigned int m_sizeReserved;	// Total size of the allocated space used to internally store the number
	unsigned int m_digitCount;	// How many digits are in the number.

	std::uint8_t getDigit(unsigned int position) const;
	void setDigit(unsigned int position, std::uint8_t digit);
};

#endif


I'll add another post with BigInteger.cpp and main.cpp
BAC Sun (14)
BigInteger.cpp

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#include <iostream>
#include <algorithm>
#include <cmath>

#include "BigInteger.hpp"


// ------------------------------------------------------------------
//
// Returns the digit as the specified positon.  If the position is greater
// that the number representation, a 0 is returned.
//
// ------------------------------------------------------------------
std::uint8_t BigInteger::getDigit(unsigned int position) const
{
	if (position < m_digitCount)
	{
		return m_number[position];
	}

	return 0;
}

void BigInteger::setDigit(unsigned int position, uint8_t digit)
{
	if (position < m_digitCount)
	{
		m_number[position] = digit;
	}
	else
	{
		if (position + 1 < m_sizeReserved)
		{
			m_digitCount = position + 1;
			m_number[position] = digit;
		}
		else
		{
			while (m_sizeReserved <= position)
			{
				m_sizeReserved *= 2;
			}
			uint8_t* copy_m_number = new uint8_t[m_sizeReserved];
			m_digitCount = position + 1;
			for (unsigned int i = 0; i < m_digitCount; ++i)
			{
				if (m_number[i] < 10)
				{
					copy_m_number[i] = m_number[i];
					m_number[i] = NULL;
				}
				else
				{
					copy_m_number[i] = 0;
				}
			}
			delete[] m_number;
			m_number = new uint8_t[m_sizeReserved];
			
			for (unsigned int i = 0; i < m_digitCount; ++i)
			{
				m_number[i] = copy_m_number[i];
				copy_m_number[i] = NULL;
			}
			delete[] copy_m_number;
			m_number[position] = digit;
		}

	}
}

BigInteger BigInteger::operator= (const BigInteger& rOther) // overridden
{
	for (unsigned int i = 0; i < m_digitCount; ++i)
	{
		this->m_number[i] = NULL;
	}
	this->m_sizeReserved = rOther.m_sizeReserved;
	this->m_digitCount = rOther.m_digitCount;
	delete[] this->m_number;
	this->m_number = new uint8_t[this->m_sizeReserved];
	for (unsigned int i = 0; i < m_digitCount; ++i)
	{
		this->setDigit(i, rOther.m_number[i]);
	}
	return *this;
}

BigInteger BigInteger::operator+(const BigInteger& rhs)
{
	BigInteger result;
	unsigned int length = (this->m_digitCount > rhs.m_digitCount) ? this->m_digitCount : rhs.m_digitCount;
	result.m_digitCount = length;
	while (result.m_digitCount > result.m_sizeReserved)
	{
		result.m_sizeReserved *= 2;
		result.m_number = new std::uint8_t[result.m_sizeReserved];
		for (unsigned int i = 0; i < result.m_digitCount; ++i)
		{
			result.setDigit(i, 0);
		}
	}
	int carry = 0;
	for (unsigned int digit = 0; digit < length; digit++)
	{
		int v1 = this->getDigit(digit);
		int v2 = rhs.getDigit(digit);
		int sum = v1 + v2 + carry;
		int single = sum % 10;
		carry = ((sum - single) > 0) ? (sum - single) / 10 : 0;

		result.setDigit(digit, single);
	}
	if (carry > 0)
	{
		result.setDigit(length, carry);
	}

	return result;
}

BigInteger BigInteger::operator+(const unsigned int& inboundInt)
{
	BigInteger rhs(inboundInt);
	BigInteger result;
	unsigned int length = (this->m_digitCount > rhs.m_digitCount) ? this->m_digitCount : rhs.m_digitCount;
	result.m_digitCount = length;
	while (result.m_digitCount > result.m_sizeReserved)
	{
		result.m_sizeReserved *= 2;
		result.m_number = new std::uint8_t[result.m_sizeReserved];
		for (unsigned int i = 0; i < result.m_digitCount; ++i)
		{
			result.setDigit(i, 0);
		}
	}
	int carry = 0;
	for (unsigned int digit = 0; digit < length; digit++)
	{
		int v1 = this->getDigit(digit);
		int v2 = rhs.getDigit(digit);
		int sum = v1 + v2 + carry;
		int single = sum % 10;
		carry = ((sum - single) > 0) ? (sum - single) / 10 : 0;

		result.setDigit(digit, single);
	}
	if (carry > 0)
	{
		result.setDigit(length, carry);
	}
	return result;
}

BigInteger BigInteger::operator+=(const BigInteger& rhs)
{
	BigInteger result = *this + rhs;
	*this = result;
	return *this;
}

BigInteger BigInteger::operator++(int)
{
	BigInteger temp = *this;
	BigInteger postfix(1);
	*this += postfix;
	return temp;
}

BigInteger BigInteger::operator*(const BigInteger& rhs)
{
	BigInteger result;
	const BigInteger& b = *this;
	const BigInteger& t = rhs;

	for (unsigned int bDigit = 0; bDigit < b.m_digitCount; bDigit++)
	{
		BigInteger temp(0);
		int v1 = b.getDigit(bDigit);
		int carry = 0;
		for (unsigned int tDigit = 0; tDigit < t.m_digitCount; tDigit++)
		{
			int v2 = t.getDigit(tDigit);
			int sum = v1 * v2 + carry;
			int single = sum % 10;
			carry = ((sum - single) > 0) ? (sum - single) / 10 : 0;

			temp.setDigit(bDigit + tDigit, single);
		}
		if (carry > 0)
		{
			temp.setDigit(bDigit + t.m_digitCount, carry);
		}
		result += temp;
	}

	return result;
}

BigInteger BigInteger::operator*=(const BigInteger& rhs)
{
	BigInteger result = *this * rhs;
	*this = result;
	return *this;
}

BigInteger::operator double()
{
	double result = 0;
	for (unsigned int i = 0; i < this->m_digitCount; ++i) 
	{
		result += (this->m_number[i] * pow(10, i));
	}
	return result;
}

bool BigInteger::operator<=(const BigInteger& rhs)
{
	if (this->m_digitCount < rhs.m_digitCount) return true;
	if (this->m_digitCount > rhs.m_digitCount) return false;
	// If m_digitCount for both are equal check digit by digit
	for (int digit = m_digitCount - 1; digit >= 0; digit--)
	{
		if (this->m_number[digit] < rhs.m_number[digit]) return true;
		if (this->m_number[digit] > rhs.m_number[digit]) return false;
	}
	//if they are equal, return true
	return true;
}

bool BigInteger::operator==(const BigInteger& rhs)
{
	if (this->m_digitCount < rhs.m_digitCount) return false;
	if (this->m_digitCount > rhs.m_digitCount) return false;
	// If m_digitCount for both are equal check digit by digit
	for (int digit = m_digitCount - 1; digit >= 0; digit--)
	{
		if (this->m_number[digit] < rhs.m_number[digit]) return false;
		if (this->m_number[digit] > rhs.m_number[digit]) return false;
	}
	//if they are equal, return true
	return true;
}

std::ostream& operator<<(std::ostream& os, const BigInteger rhs)
{
	for (unsigned int digit = rhs.m_digitCount; digit > 0; digit--)
	{
		std::cout << static_cast<int>(rhs.m_number[digit - 1]);
	}
	return os;
}


Main.cpp

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#include <iostream>

#include "BigInteger.hpp"

// ------------------------------------------------------------------
//
// Site to compare long factorial results: http://www.dcode.fr/factorial
//
// ------------------------------------------------------------------
BigInteger factorial(BigInteger value)
{
	BigInteger result(1);

	for (BigInteger next = 1; next <= value; next++)
	{
		result *= next;
	}

	return result;
}

int main()
{
	BigInteger one(1234);
	BigInteger two(9999);
	BigInteger result = one + two;
	std::cout << "one + two = " << result << std::endl;
	std::cout << "one + two (as double) = " << static_cast<double>(result) << std::endl;
	one += two;
	std::cout << "one += two = " << one << std::endl;
	
	BigInteger three("1234567890");
	BigInteger four("123456789");
	BigInteger result2 = three * four;
	std::cout << "three * four = " << result2 << std::endl;
	three *= four;
	std::cout << "three *= four = " << three << std::endl;
	
	BigInteger f = factorial(123);
	std::cout << "factorial of 123 is: " << f << std::endl;
	std::cout << "factorial (as double) = " << static_cast<double>(f) << std::endl;
	BigInteger factorialFromWeb("12146304367025329675766243241881295855454217088483382315328918161829235892362167668831156960612640202170735835221294047782591091570411651472186029519906261646730733907419814952960000000000000000000000000000");

	if (f == factorialFromWeb)
	{
		std::cout << "My factorial result matches!!" << std::endl;
	}
	else
	{
		std::cout << "Still work left to do..." << std::endl;
	}

	return 0;
}
BAC Sun (14)
The problem was in my overloaded + and my setdigit functions apparently. I made the following changes to my + operators:
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BigInteger result;
	unsigned int length = (this->m_digitCount > rhs.m_digitCount) ? this->m_digitCount : rhs.m_digitCount;
	result.m_digitCount = length;
	while (result.m_digitCount > result.m_sizeReserved)
	{
		result.m_sizeReserved *= 2;
		delete[] result.m_number;
		result.m_number = new uint8_t[result.m_sizeReserved];
	}
// the rest of the function remained the same

That solved most of it, but I was still getting heap corruption on occasion, so I played around a bit more. I ended up removing all of the m_number[i] = NULL; from my setdigit and overloaded function. I'm not having any more heap corruption so I suppose it was causing excessive calls to delete.
Last edited on
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