c++ - Cascading overloaded cout operator error `No match` when used with other overloaded operators -

i have overloaded << in code friend function. after using braces while cascading there still error

error: no match ‘operator<<’ in ‘std::operator<< [with _traits =  std::char_traits<char>]((* & std::cout), ((const char*)"complex conjugate "))  << c.mycomplex::operator~()’ 

i have class mycomplex

class mycomplex {     private:     float real;     float imaginary;          public:     mycomplex();     mycomplex(float a,float b);     friend std::ostream& operator<<(std::ostream& iso,mycomplex& a);     mycomplex operator~() const; }; 

the overload <<, ~and constructors follows,

std::ostream& operator<<(std::ostream& oso,mycomplex& a) {     oso<<a.real<<" + "<<a.imaginary<<"i"<<std::endl; return oso; }  mycomplex mycomplex::operator~() const {     return mycomplex(this->real,-1*this->imaginary); }  mycomplex::mycomplex(float a,float b) {     real = a;     imaginary = b; } 

i use in main follows,

line 1:    std::cout << "c " << c << "\n"; line 2:    std::cout << "a " << << "\n"; 

line 3: ((std::cout <<"complex conjugate ")<<(~c))<<"\n";

line 3:    std::cout <<"complex conjugate "<<~c<<"\n"; 

line 1 , 2 work fine, line 3 gives error. if can cascade line 1 , 2 , since ~c returns ostream why give error that?

because operator~() returns value, feeding temporary object ostream& operator<< here:

std::cout <<"complex conjugate "<< ~c <<"\n"; //                                    ^^ here! temporary mycomplex value. 

the operator takes 2nd argument non-const reference mycomplex&. non-const reference cannot bind temporary. change to

std::ostream& operator<<(std::ostream& oso, const mycomplex& a);