Conflicting declaration error

[JohnnyTest]

Hi everyone,

I am still stuck at using templates inside class. I'm trying to make a BigNumber library in C++ for learning purpose.

my code is:


BigInt.h

#include <iostream>
#include <string>

/**Specifications:
*   stores number as: intgr for int part and dec for decimal part
*   member sign is 1 for positive number and -1 for negative and 0 for Not a Number i.e. NaN
*   Constructor: can take, int, string(formatted as number), float or double
*   operators to define +, -, *, /, %, power(), <<, >>
*/

namespace GG
{

    class BigInt
    {
    public:
        /** Default constructor */
        BigInt();

        template<typename T>
        BigInt(const T&);

        /** Default destructor */
        virtual ~BigInt();

        /** Copy constructor
        *  \param other Object to copy from
        */
        BigInt(const BigInt& other);

        /** Assignment operator
        *  \param other Object to assign from
        *  \return A reference to this
        */
        BigInt& operator=(const BigInt& other);

        friend std::ostream& operator<<(std::ostream& os, const BigInt& bigInt);
        friend std::istream& operator>>(std::istream& is, BigInt& bigInt);

    protected:

    private:
        /**
        *   Number is represented as:
        *   +0.123324 or -0.1232432
        *   +123 or -123 etc
        *   [+ or -] then [numbers] then maybe [.] then [more numbers]
        */

        std::string intgr; // Integer part of number i.e. 23 in 23.45
        std::string dec; // decimal part of number i.e. 45 in 23.45
        short sign; // 1 for positive number, -1 for negative and 0 for NaN (Not a Number)
    };

    template<typename T>
    BigInt::BigInt(const T& n)
    {
        std::string num_str = std::to_string(n); // |note: previous declaration as ‘std::__cxx11::string num_str’|
        BigInt(num_str); // |error: conflicting declaration ‘GG::BigInt num_str’|
    }


    //Specialiazed for string
    template<> inline
    BigInt::BigInt<std::string>(const std::string& str)
    {
        BigInt();
    }

    //Specialized for char
    template<> inline
    BigInt::BigInt<char>(const char& ch)
    {
        BigInt();
    }

}// namespace GG ends here

BigInt.cpp

#include "BigInt.h"

#include <string>
#include <regex>

namespace GG
{

    #define DEBUG_SYMS
    #undef DEBUG_SYMS

    BigInt::BigInt()
    {
        //ctor
        dec = "NaN";
        intgr = "NaN";
        sign = 0;
    }


    BigInt::~BigInt()
    {
        //dtor
    }

    BigInt::BigInt(const BigInt& other)
    {
        //copy ctor
    }

    BigInt& BigInt::operator=(const BigInt& rhs)
    {
        if (this == &rhs) return *this; // handle self assignment
                                        //assignment operator
        this->intgr = rhs.intgr;
        this->dec = rhs.dec;
        this->sign = rhs.sign;
        return *this;
    }

    std::ostream& operator<<(std::ostream& os, const BigInt& bigInt)
    {
        std::string num_str = "";
        if(bigInt.sign == 0)
        {
            os << "NaN";
            return os;
        }
        else if(bigInt.sign == -1)
            num_str = "-";
        num_str += bigInt.intgr;
        if(bigInt.dec != "0")
        {
            num_str += ".";
            num_str += bigInt.dec;
        }
        os << num_str;

        return os;
    }

    std::istream& operator>>(std::istream& is, BigInt& bigInt)
    {
        std::string input_num;
        is>>input_num;
        bigInt = BigInt(input_num);
        return is;
    }

}// namespace GG ends here

main.cpp

#include <iostream>

#include "BigInt.h"

using namespace std;

int main()
{

         short short_n = 123;
	GG::BigInt n(short_n);
	GG::BigInt n_default;
	std::cout << n << " " << n_default ;
	return 0;
}

I have written all the code for the sake of completeness so that you could reproduce the problem. But you need to look mainly in BigInt.h in which I am facing problem in specialized string contructor.

errors are as follows:
1. ||error: conflicting declaration ‘GG::BigInt num_str’||
2. ||note: previous declaration as ‘std::__cxx11::string num_str’||

Please guide me.