C++ In a Nutshell

Name

slice_array class template — Helper class for slice

Synopsis

template <typename T>
class slice_array {
public:
  typedef T value_type;
  void operator=(const valarray<T>&) const;
  void operator*=(const valarray<T>&) const;
  void operator/=(const valarray<T>&) const;
  void operator%=(const valarray<T>&) const;
  void operator+=(const valarray<T>&) const;
  void operator-=(const valarray<T>&) const;
  void operator^=(const valarray<T>&) const;
  void operator&=(const valarray<T>&) const;
  void operator|=(const valarray<T>&) const;
  void operator<<=(const valarray<T>&) const;
  void operator>>=(const valarray<T>&) const;
  void operator=(const T&);
  ~slice_array(  );
private:
  slice_array(  );
  slice_array(const slice_array&);
  slice_array& operator=(const slice_array&);
};

The slice_array class template represents a subset of the elements of a valarray, taken at periodic indices, called a slice. To create a slice, use valarray’s operator[] with an argument of type slice.

For some operations, the slice_array object is transparent. In particular, you can assign a valarray to a slice_array object (provided they have the same size), or you can construct a new valarray from a slice_array.

If you want to perform other operations, such as non-assignment arithmetic, you must explicitly convert the slice_array to valarray, as demonstrated in Example 13-47.

Example

Example 13-47. Slicing a valarray

int main( ) { using namespace std; const int data[] = { 1,2,3,4,5,6,7,8,9,10,11,12,13 }; valarray<int> v(data, sizeof(data)/sizeof(data[0])); ...