template <class T> struct plus;

<functional>

Addition function object class

This class defines function objects for the addition arithmetic operation.

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 regular function call, and therefore it can be used in templates instead of a pointer to a function.

plus has its operator() member defined such that it returns the addition of its two arguments.

This class is derived from binary_function and is defined as:

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

Objects of this class can be used with some standard algorithms such as transform or accumulate.

Members

T operator() (const T& x, const T& y)

Member function returning the sum of its two arguments (x+y).

Example

// plus example
#include <iostream>
#include <functional>
#include <algorithm>
using namespace std;

int main () {
  int first[]={1,2,3,4,5};
  int second[]={10,20,30,40,50};
  int results[5];
  transform ( first, first+5, second, results, plus<int>() );
  for (int i=0; i<5; i++)
	  cout << results[i] << " ";
  cout << endl;
  return 0;
}

Output:

11 22 33 44 55

See also