Parametrized Template Class constructor with another template class-CodePudding

I am trying to initialize a Calculator with two Complex variables. Both these classes are template classes.

calculator.h

#ifndef CALCULATOR_H
#define CALCULATOR_H

template <class U>
class Calculator{
    private:
        U left_val;
        U right_val;
    public:
        Calculator(){}
        Calculator(U m_left_val, U m_right_val){
            left_val = m_left_val;
            right_val = m_right_val;
        }
        U add();
        U subtract();
};

#endif

complex.h

#ifndef COMPLEX_H
#define COMPLEX_H

template <class T>
class Complex{
    private:
        T m_real;
        T m_imaginary;
    public:
        Complex(){}
        Complex(T real = 0 , T imaginary = 0){
            m_real = real;
            m_imaginary = imaginary;
        }
        Complex operator   (const Complex& complex);
        Complex operator - (const Complex& complex);
};

#endif

In my main:

Calculator<double> floatCalc(30.3, 20.7);
Calculator<int> intCalc(100, 30);
Complex<double> a(2.0, 4.0);
Complex<double> b(1.0, 2.0);
Calculator<Complex<double>> complexCalc(a, b); //This is the line in question

I am getting two compile time errors that only relate to the initialization of complexCalc and they are the same error:

In file included from main.cpp:3:
calculator.h: In instantiation of 'Calculator<U>::Calculator() [with U = Complex<double>]':
main.cpp:11:33:   required from here
calculator.h:10:21: error: call of overloaded 'Complex()' is ambiguous
   10 |         Calculator(){}
      |                     ^
In file included from main.cpp:2:
complex.h:11:9: note: candidate: 'Complex<T>::Complex(T, T) [with T = double]'
   11 |         Complex(T real = 0 , T imaginary = 0){
      |         ^~~~~~~
complex.h:10:9: note: candidate: 'Complex<T>::Complex() [with T = double]'
   10 |         Complex(){}
      |         ^~~~~~~
In file included from main.cpp:3:
calculator.h:10:21: error: call of overloaded 'Complex()' is ambiguous
   10 |         Calculator(){}
      |                     ^
In file included from main.cpp:2:
complex.h:11:9: note: candidate: 'Complex<T>::Complex(T, T) [with T = double]'
   11 |         Complex(T real = 0 , T imaginary = 0){
      |         ^~~~~~~
complex.h:10:9: note: candidate: 'Complex<T>::Complex() [with T = double]'
   10 |         Complex(){}
      |         ^~~~~~~

I don't know what this means or how to fix it.

CodePudding user response：

The issue is that there's no way to differentiate between the zero parameter constructor of Calculator, and the two parameter constructor with default arguments. You should just remove your zero parameter constructor.