Issue with overloaded output operator

[goldenchicken]

Hi everyone!

I'm writing a BigInt class (now with a vector containing the digits, instead of a string), and my program crashes when I try to use the overloaded output operator. First it outputs alot of garbage numbers, and then the program crashes. Can anyone help me with this?

//BigInt.h
#ifndef BIGINT_H
#define BIGINT_H
#include <vector>
#include <string>
#include <iostream>
class BigInt
{
private:
	std::vector<int> m_digits;
public:
	BigInt(int digits);
	friend std::ostream& operator<<(std::ostream &out, const BigInt &bigInt); 
};
#endif

//BigInt.cpp
#include "BigInt.h"

BigInt::BigInt(int digits)
{
	//store the number in reverse order, this makes it easier to calculate the 'real' value of every digit
	std::string digits_s = std::to_string(digits);
	for (std::size_t i; i < digits_s.length(); ++i)
		m_digits.push_back(digits_s[i]);
}
/*OPERATORS*/

/*Input/Output operators*/

std::ostream& operator<<(std::ostream &out, const BigInt &bigInt)
{
	for (std::size_t i = (bigInt.m_digits).size()-1; i >= 0; --i)
	{
		out << (bigInt.m_digits)[i];
	}
	return out;
}
//main source file for testing
#include "BigInt.h"
#include <iostream>
int main()
{
	BigInt a(123);
	std::cout << a;
	return 0;
}

Thanks

[Peter87]

There is no way for the condition i >= 0 to be false because std::size_t is an unsigned type which means it cannot store negative values.

Another problem is that you've forgot to initialize i in the constructor.