In code:

LINT a = "12";
LINT b = 3;
a = "3";//WHY THIS LINE INVOKES CTOR?

std::string t = "1";
//LINT a = t;//Err NO SUITABLE CONV FROM STRING TO LINT. Shouldn't ctor do it?

#pragma once
#include "LINT_rep.h"
class LINT
{
private:
    typedef LINT_rep value_type;
    const value_type* my_data_;
    template<class T>
    void init_(const T&);
public:
    LINT(const char* = 0);
    LINT(const std::string&);
    LINT(const LINT&);
    LINT(const long_long&);
    LINT& operator=(const LINT&);
    virtual ~LINT(void);

    LINT operator+()const;               //DONE
    LINT operator+(const LINT&)const;//DONE
    LINT operator-()const;               //DONE
    LINT operator-(const LINT&)const;//DONE
    LINT operator*(const LINT&)const;//DONE
    LINT operator/(const LINT&)const;///WAITS FOR APPROVAL

    LINT& operator+=(const LINT&);//DONE
    LINT& operator-=(const LINT&);//DONE
    LINT& operator*=(const LINT&);//DONE
    LINT operator/=(const LINT&);///WAITS FOR APPROVAL
};

in line number 3 instead of assignment optor ctor is invoked. Why? I'm willing to uppload entire solution on some server otherwise it's hard to put everything in here. I can also upload video file. Another thing is that when I implement this assignment optor I'm getting an error that this optor is already in obj file? What's going on?