The single operators operate on one quantity and following are the samples of single operators − - The increment ( ) and decrement (--) operators. The compiler distinguishes between the different meanings of an operator by examining the types of its operands.
The unary operators operate on a single operand and following are the examples of Unary operators −
- The increment (++) and decrement (--) operators.
- The unary minus (-) operator.
- The logical not (!) operator.
The unary operators operate on the object for which they were called and normally, this operator appears on the left side of the object, as in !obj, -obj, and ++obj but sometimes they can be used as postfix as well like obj++ or obj--.
Following example explain how bang(!) operator can be overloaded for prefix usage −
Example
#include <iostream>
using namespace std;
class Distance {
private:
int feet; // 0 to infinite
int inches; // 0 to 12
public:
// Constructor
Distance(int f, int i) {
feet = f;
inches = i;
}
// method to display distance
void display() {
cout << "F: " << feet << " I:" << inches <<endl;
}
// overloaded bang(!) operator
Distance operator!() {
feet = -feet;
inches = -inches;
return Distance(feet, inches);
}
};
int main() {
Distance D1(3, 4), D2(-1, 10);
!D1;
D1.display(); // display D1
!D2; // apply negation
D2.display(); // display D2
return 0;
}Output
This will give the output −
F: -3 I:-4 F: 1 I:-10