C++ Overloaded operations and Conversions

Overloaded operators Must have an operand of Class Type

//error:can not redefine built-in operator for ints int operator+(int,int);

Overloading the Input/Output operator

The general skeleton of overloaded input/output operator is

istream& operator >>(istream& in,ClaaType& s) { int something; in>>s.~~~>>s.~~~>>something //~~~ is represent the data member of the class } ostream& operator <<(ostream& os,const ClassType &Object) { os<<"what you want to output?"; return os; }

 

Overloaded Assignment Operators

class String { int a,b,c; string str1,str2,str3; public: String& operator=(const String&); //s1=s2 String& operator=(const char*); //s1="str" String& operator=(char); //s1='c' //... }; //Assignment should return a reference to *this String& String::operator +=(const String& rhs) { str1 += rhs.str1; str2 += rhs.str2; return *this; }

 

Overloaded  Increment and Decrement Operators

Class test { public: test& operator ++(); //prefix operators test& operator--(); public: test operator++(int); //postfix operators test operator--(int); } //Calling the Prefic/Postfix operators Explicitly test t(arr,arr+size); //arr points to an array of ints t.operator++(0); //call postfix operator++ t.operator++(); //call prefix operator++

 

 

Conversions and Class Types ---A simple example

class Integral { public: Integral (int i=0) : val(i) {} operator int() const { return val; } //return a int private: std::size_t val; }; //A conversion function takes the general form operator type(); //All of the following declarations are errors: operator int(Integral&); //error:nonmember int operator int(); //erroe: return type operator int (int=0); //error:parameter list