C + + Copy constructors

classComplex {Private :    DoubleM_real; DoubleM_imag; Public:     //parameterless Constructors//If you create a class and you do not write any constructors, the system automatically generates the default parameterless constructor, the function is empty, and nothing is done//as long as you write one of the following constructors, the system will no longer automatically generate such a default constructor, if you want to have such a parameterless constructor, you need to write it yourselfComplex (void) {M_real=0.0; M_imag=0.0; }              //General Constructors (also called overloaded constructors)//General constructors can have a variety of parameter forms, a class can have more than one general constructor, if the number of parameters or different types (based on the principle of overloaded functions of C + +)//For example: You can also write a Complex (int num) constructor .//different constructors are called depending on the parameters passed in when the object is createdComplex (DoubleRealDoubleimag) {M_real=Real; M_imag=Imag; }         //Copy Constructors (also known as copy constructors)//A copy constructor parameter is a reference to the class object itself that copies a new object of that class based on an existing object, typically copying the value of the data member of an existing object into the newly created object in the function//If you do not see a write-copy constructor, the system creates a copy constructor by default, but when there are pointer members in the class, there is a risk that the copy constructor is created by default, for specific reasons, please inquire about "shallow copy", "Deep copy" article discussionComplex (ConstComplex &c) {//Copy the value of the data member in Object C.M_real =C.m_real; M_img=c.m_img; }                 //A type conversion constructor that creates an object of this class based on an object of a specified type//For example: The following will create a complex object based on an object of type doubleComplex::complex (Doubler) {m_real=R; M_imag=0.0; }     //equals operator overload//Note that this is similar to the copy constructor, which copies the value of the object of this class = Right to the object to the left of the equals sign, which is not a constructor, and the object on both sides of the equal sign must have been created//if the Write = operator overload is not displayed, the system also creates a default = operator overload, doing only basic copy workComplex &operator=(ConstComplex &RHS) {        //first detect whether the right side of the equal sign is the object of the left, if the object itself, the direct return        if( This= = &RHS) {            return* This; }                     //copy the member to the right of the equal sign to the left object         This->m_real =Rhs.m_real;  This->m_imag =Rhs.m_imag; //send the object to the left of the equal sign again//The purpose is to support the EG:A=B=C system to run first B=c//then run a= (the return value of B=c, which should be the B object after the C value is copied)        return* This; }};

C + + Copy constructors