Reference
C Library
IOstream Library
Strings library
STL Containers
STL Algorithms
Miscellaneous

Miscellaneous
complex
exception
functional
iterator
limits
locale
memory
new
numeric
stdexcept
typeinfo
utility
valarray

valarray
classes:
gslice
gslice_array
indirect_array
mask_array
slice
slice_array
valarray
global functions:
abs
acos
asin
atan
atan2
cos
cosh
exp
log
log10
pow
sin
sinh
sqrt
tan
tanh

slice_array

class template

<valarray>

template <class T> slice_array;

Valarray slice selection

This class is used as an intermediate type returned by the non-constant version of valarray's subscript operator (valarray operator[] ) when used with slices.

It contains references to the elements in the valarray object that are selected in a slice, and overloads the assignment and compound assignment operators, allowing direct access to the elements in the selection when used as l-value (left-value of an assignment operation).

When used as r-value (right-value of an assignment operation), it can initialize a valarray object, since valarray has a constructor taking a slice_array object as argument.

All the constructors of this class are private, preventing direct instantiations by a program - its only purpose is to be an efficient way to access the elements selected by a slice with valarray's operator[] .

It is declared as:

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

template <class 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&);
};

Example

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

// slice_array example
#include <iostream>
#include <valarray>
using namespace std;
int main ()
{
  valarray<int> foo (9);
  slice myslice;
  for (int i=0; i<9; ++i) foo[i]=i;      //  0  1  2  3  4  5  6  7  8
                                         //     |     |     |
  myslice=slice(1,3,2);                  //     v     v     v
  foo[myslice] *= valarray<int>(10,3);   //  0 10  2 30  4 50  6  7  8
                                         //  |        |        |
  myslice = slice (0,3,3);               //  v        v        v
  foo[myslice] = 99;                     // 99 10  2 99  4 50 99  7  8
  cout << "foo:\n";
  for (size_t n=0; n<foo.size(); n++)
	  cout << foo[n] << ' ';
  cout << endl;
  return 0;
}

Output:


99 10 2 99 4 50 99 7 8

slice_array

Example

See also