A valarray slice is defined by a starting index, a size, and a stride.

The starting index (start) is the index of the first element in the selection.
The size (size) is the number of elements in the selection.
The stride (stride) is the span that separates the elements selected.

Therefore, a slice with a stride higher than 1 does not select contiguous elements in the valarray; For example, slice(3,4,5) selects the elements 3, 8, 13 and 18.

Member functions

(constructor)

slice constructor (public member function)

slice::start

Return start of slice (public member function)

slice::size

Return size of slice (public member function)

slice::stride

Return stride of slice (public member function)

Example

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// slice example
#include <iostream>     // std::cout
#include <cstddef>      // std::size_t
#include <valarray>     // std::valarray, std::slice

int main ()
{
  std::valarray<int> foo (12);
  for (int i=0; i<12; ++i) foo[i]=i;

  std::valarray<int> bar = foo[std::slice(2,3,4)];

  std::cout << "slice(2,3,4):";
  for (std::size_t n=0; n<bar.size(); n++)
	  std::cout << ' ' << bar[n];
  std::cout << '\n';

  return 0;
}

See also

gslice

Valarray generalized slice selector (class)

slice_array

Valarray slice selection (class template)