operators

 

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Operator Overloading

Syntax

type operator op ( params ) ;

Explanation

• <type> is/are the type(s) of the variables.
• <op> is the particular operator (e.g. +, +=, <<, >>, &&, ||, %, etc.).
• <params> is/are the name(s) of the required parameters (depends on the operator).

Restrictions

• You cannot create new operators such as ** or &|.
• Not all operators can be overloaded
• Some operators can only be overloaded as non-static class members
• Short-circuit evaluation doesn't work with overloaded operators

Operator Calls

Overloaded operators can be called using the usual infix notation

a+b

or a function-like notation

operator+(a,b)

Example

#include <iostream>
 using namespace std;
 
 class Fraction{
   private:
     int numerator, denominator;
 
   public:
     Fraction(int n, int d): numerator(n), denominator(d) {}
   // Note that the keyword operator combined with an actual
   // operator is used as the function name
   friend ostream& operator<<(ostream&, Fraction&);
 };
 
 ostream& operator<<(ostream& out, Fraction& f){
   out << f.numerator << '/' << f.denominator;
   return out;
 }
 
 int main(){
   Fraction f1(3, 8);
   Fraction f2(1, 2);
 
   cout << f1 << endl;
   cout << 3 << ' ' << f2 << endl;
 
   return 0;
 }

Output:

3/8
3 1/2

See Also

• Operator precedence
• Alternative operator syntax

Common operators
assignment	increment decrement	arithmetic	logical	comparison	member access	other
a = b a = rvalue a += b a -= b a *= b a /= b a %= b a &= b a |= b a ^= b a <<= b a >>= b	++a --a a++ a--	+a -a a + b a - b a * b a / b a % b ~a a & b a | b a ^ b a << b a >> b	!a a && b a || b	a == b a != b a < b a > b a <= b a >= b	a[b] *a &a a->b a.b a->*b a.*b	a(...) a, b (type) a ? :
Special operators
static_cast converts one type to another compatible type dynamic_cast converts virtual base class to derived class const_cast converts type to compatible type with different cv qualifiers reinterpret_cast converts type to incompatible type new allocates memory delete deallocates memory sizeof queries the size of a type sizeof... queries the size of a parameter pack (since C++11) typeid queries the type information of a type noexcept checks if an expression can throw an exception (since C++11) alignof queries alignment requirements of a type (since C++11)