Реализовать класс "Длинных чисел" (найти причины и способы устранения ошибки)

#include <iostream>
#include <deque>
#include <string>
using namespace std;
 
 
class Longnum
{
public:
    void vector_print(Longnum &);
    int sravnenie(Longnum, Longnum);
    Longnum();
    Longnum(string, string);
    Longnum(Longnum&);
    ~Longnum();
    Longnum dell_null(Longnum &);
    Longnum proisvedenie(Longnum &, Longnum &);
    Longnum delenie(Longnum &, Longnum &);
    Longnum& operator+ (Longnum &);
    Longnum& operator- (Longnum &);
private:
    deque <int> vector;
    char znak;
};

#include "ClassLong.h"
#include <deque>
 
using namespace std;
 
Longnum::Longnum()
{
    cout << "Default constructor" << endl;
}
 
Longnum::Longnum(string temp, string minus)
{
    Longnum big;
    string str;
    cin >> str;
    if (str.at(0) == minus.at(0)) big.znak = '-';
    for (int i = 0; i<(int)str.length(); i++)
    for (int j = 0; j < 10; j++)
    if (str.at(i) == temp.at(j)) big.vector.push_back(j);
}
void Longnum::vector_print(Longnum &big)
{
    
    if (big.vector.size() == 1 && big.vector.at(0) == ' ') { big.znak = ' '; cout << big.znak; }
    if (big.znak == '-')
        cout << big.znak;
    for (int i = 0; i < big.vector.size(); i++)
        cout << (int)big.vector.at(i);
}
Longnum::Longnum(Longnum& big)
{
    vector.clear();
    for (int i = 0; i < big.vector.size(); i++)
        vector.push_back(big.vector[i]);
}
int Longnum::sravnenie(Longnum big1, Longnum big2)
{
 
}
Longnum dell_null(Longnum big)
{
 
}
Longnum proisvedenie(Longnum big1, Longnum big2)
{
 
}
Longnum delenie(Longnum delimoe, Longnum delitel)
{
 
}
Longnum& Longnum::operator+(Longnum &other)
{
 
}
Longnum& Longnum::operator-(Longnum &other)
{
 
}

#include <clocale>
#include <iostream>
#include "ClassLong.h"
#include "ClassLong.cpp"
 
using namespace std;
 
void main()
{
    setlocale(LC_ALL, "Russian");
    
    Longnum long1;
    Longnum("0123456789", "-");
    long1.vector_print(long1);
    system("pause");
}