std::slice_array

template <class T> slice_array;

Valarray slice selection

This class is used as an intermediate type returned by valarray 's subscript operator (operator[]) when used with slices .

It references the elements in the valarray object that are selected by the slice , and overloads the assignment and compound assignment operators, allowing direct access to the elements in the selection.

The type is convertible to a valarray (see valarray constructor ), producing a new object with copies of the referred elements.

Objects of this type are obtained as the return value of a call to valarray::operator[] . They cannot be directly constructed nor copied. It is declared as:

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& val);
 ~slice_array();
private:
 slice_array();
 slice_array(const slice_array&);
 slice_array& operator= (const slice_array&);
};

Objects of this type are obtained as the return value of a call to valarray::operator[] . They cannot be default-constructed, but can be copied. It is declared as:

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&) const;
 slice_array() = delete;
 slice_array(const slice_array&);
 const slice_array& operator= (const slice_array&) const;
 ~slice_array();
};

Example

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

Output:


99 10 2 99 4 50 99 7 8

classes

functions

std::slice_array

Example

See also