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Showing content from https://cplusplus.com/reference/functional/logical_or/ below:

class template

std::logical_or

template <class T> struct logical_or;

Logical OR function object class

Binary function object class whose call returns the result of the logical "or" operation between its two arguments (as returned by operator ||).

Generically, function objects are instances of a class with member function operator() defined. This member function allows the object to be used with the same syntax as a function call.

It is defined with the same behavior as:

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template <class T> struct logical_or : binary_function <T,T,bool> {
  bool operator() (const T& x, const T& y) const {return x||y;}
};

template <class T> struct logical_or {
  bool operator() (const T& x, const T& y) const {return x||y;}
  typedef T first_argument_type;
  typedef T second_argument_type;
  typedef bool result_type;
};

Template parameters

T: Type of the arguments passed to the functional call.
The type shall support the operation (operator||).

Member types member type definition notes first_argument_type T Type of the first argument in member operator() second_argument_type T Type of the second argument in member operator() result_type bool Type returned by member operator()
Member functions

bool operator() (const T& x, const T& y): Member function returning whether any of its arguments are considered true (x||y).

Example

// logical_or example
#include <iostream>     // std::cout, std::boolalpha
#include <functional>   // std::logical_or
#include <algorithm>    // std::transform

int main () {
  bool foo[] = {true,false,true,false};
  bool bar[] = {true,true,false,false};
  bool result[4];
  std::transform (foo, foo+4, bar, result, std::logical_or<bool>());
  std::cout << std::boolalpha << "Logical OR:\n";
  for (int i=0; i<4; i++)
    std::cout << foo[i] << " OR " << bar[i] << " = " << result[i] << "\n";
  return 0;
}

Output:

Logical OR:
true OR true = true
false OR true = true
true OR false = true
false OR false = false