std::complex::operator=
From cppreference.com
                    
                                        
                    
                    
                                                            
                    |   complex<T>& operator=( const T& x ); 
 | 
(1) | |
|   complex<T>& operator=( const complex<T>& cx ); 
 | 
(2) | |
Assigns new values to the contents.
1) Assigns 
x to the real part of the complex number. Imaginary part is set to zero.
2) Assigns 
cx.real() and cx.imag() to the real and the imaginary parts of the complex number respectively.[edit] Parameters
| x | - | value to assign | 
| cx | - | complex value to assign | 
[edit] Return value
*this