How do you use a assignment statement?

Answer 1

Assignment is not a statement, it is an operator. You use the assignment operator in assignment expressions.

int x = 100; // assigns the value 100 to the memory location referred to by x.

int y = x; // assigns the value of x (100) to the memory location referred to by y.

Classes can override and overload the assignment operator to ensure correct assignment behaviour, particularly important when the class includes a member pointer to memory owned by an instance of the class, or to ensure correct typecasting between objects of different types.

class MyClass{

public:

MyClass():m_pNum=new int(){} // default ctor

MyClass(const MyClass):m_pNum=new int(*MyClass.m_pNum){} // copy ctor

~MyClass(){ delete( m_pNum ); } // dtor

public:

MyClass & operator= (int); // typecast assignment

MyClass & operator= (MyClass &); // standard assignment

private:

int * m_pNum; // memory allocated by constructors.

};

// Assignment operator override required to typecast an integer.

MyClass & MyClass::operator= (int num){

*m_pNum = num;

return( *this );

}

// Assignment operator override required to ensure two instances

// of MyClass do not share the same memory.

MyClass & MyClass::operator= (MyClass & myClass){

*m_pNum = *myClass.m_pNum;

return( *this );

}