public member function

std::valarray::sum

Return sum of elements

Returns the sum of all the elements in the valarray, as if calculated by applying operator+= to a copy of one element and all the other elements, in an unspecified order.

If the valarray has a size of zero, it causes undefined behavior.

T shall support the calls to operator+=.

Parameters

none

Return value

The sum of all the elements in the valarray.
T is the template argument of valarray (the value type).

Example

// valarray::sum example
#include <iostream>     // std::cout
#include <valarray>     // std::valarray

int main ()
{
  int init[]={10,20,30,40};
  std::valarray<int> myvalarray (init,4);
  std::cout << "The sum is " << myvalarray.sum() << '\n';

  return 0;
}

Output:

Complexity

Depends on library implementation (operations may be parallelized).

Iterator validity

No changes: Valid iterators, references and sub-arrays keep their validity.

Data races

Both the valarray and its elements are accessed.

Exception safety

If applying operator+= to element values throws an exception, it causes undefined behavior.
If the valarray has a size of zero, it causes undefined behavior.