complex

template<class T>
    class complex {
public:
    typedef T value_type;
    T real() const;
    T imag() const;
    complex(const T& re = 0, const T& im = 0);
    complex(const complex& x);
    complex& operator=(const complex& rhs);
    complex& operator+=(const complex& rhs);
    complex& operator-=(const complex& rhs);
    complex& operator*=(const complex& rhs);
    complex& operator/=(const complex& rhs);
    complex& operator=(const T& rhs);
    complex& operator=(const T& rhs);
    complex& operator+=(const T& rhs);
    complex& operator-=(const T& rhs);
    complex& operator*=(const T& rhs);
    complex& operator/=(const T& rhs);
    friend complex<T>
        operator+(const complex<T>& lhs, const T& rhs);
    friend complex<T>
        operator+(const T& lhs, const complex<T>& rhs);
    friend complex<T>
        operator-(const complex<T>& lhs, const T& rhs);
    friend complex<T>
        operator-(const T& lhs, const complex<T>& rhs);
    friend complex<T>
        operator*(const complex<T>& lhs, const T& rhs);
    friend complex<T>
        operator*(const T& lhs, const complex<T>& rhs);
    friend complex<T>
        operator/(const complex<T>& lhs, const T& rhs);
    friend complex<T>
        operator/(const T& lhs, const complex<T>& rhs);
    friend bool operator==(const complex<T>& lhs, const T& rhs);
    friend bool operator==(const T& lhs, const complex<T>& rhs);
    friend bool operator!=(const complex<T>& lhs, const T& rhs);
    friend bool operator!=(const T& lhs, const complex<T>& rhs);
    };

The template class describes an object that stores two objects of type T, one that represents the real part of a complex number and one that represents the imaginary part. An object of class T:

• Has a public default constructor, destructor, copy constructor, and assignment operator -- with conventional behavior.
• Can be assigned integer or floating-point values, or type cast to such values -- with conventional behavior.
• Defines the arithmetic operators defined for the floating-point types -- with conventional behavior.

Explicit specializations of template class complex exist for the three floating-point types. In this implementation, a value of any other type T is type cast to double for actual calculations, with the double result assigned back to the stored object of type T.