C++ Utility Library - rel_ops Function

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Description

It is a relational operator.

Declaration

Following is the declaration for std::rel_ops function.

namespace rel_ops {
   template <class T> bool operator!= (const T& x, const T& y);
   template <class T> bool operator>  (const T& x, const T& y);
   template <class T> bool operator<= (const T& x, const T& y);
   template <class T> bool operator>= (const T& x, const T& y);
}

C++11

namespace rel_ops {
   template <class T> bool operator!= (const T& x, const T& y);
   template <class T> bool operator>  (const T& x, const T& y);
   template <class T> bool operator<= (const T& x, const T& y);
   template <class T> bool operator>= (const T& x, const T& y);
}

Parameters

T − It is a type and the type shall be EqualityComparable.

Return Value

none

Exceptions

none

Data races

none

Example

In below example explains about std::rel_ops function.

#include <iostream>
#include <utility>
#include <cmath>

class vector2d {
   public:
      double x,y;
      vector2d (double px,double py): x(px), y(py) {}
      double length() const {return std::sqrt(x*x+y*y);}
      bool operator==(const vector2d& rhs) const {return length()==rhs.length();}
      bool operator< (const vector2d& rhs) const {return length()< rhs.length();}
};

int main () {
   using namespace std::rel_ops;
   vector2d a (10,10);
   vector2d b (15,20);
   std::cout << std::boolalpha;
   std::cout << "(a>b) is " << (a<b) << '\n';
   std::cout << "(a<b) is " << (a>b) << '\n';
   return 0;
}

Let us compile and run the above program, this will produce the following result −

(a>b) is true
(a<b) is false