# 28 Numerics library [numerics]

## 28.6 Numeric arrays [numarray]

### 28.6.5 Class template slice_array[template.slice.array]

#### 28.6.5.1 Overview [template.slice.array.overview]

namespace std { template<class T> class slice_array { public: using value_type = T; 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; slice_array(const slice_array&); ~slice_array(); const slice_array& operator=(const slice_array&) const; void operator=(const T&) const; slice_array() = delete; // as implied by declaring copy constructor above }; }
This template is a helper template used by the slice subscript operator slice_array<T> valarray<T>::operator[](slice);
It has reference semantics to a subset of an array specified by a slice object.
[Example 1:
The expression a[slice(1, 5, 3)] = b; has the effect of assigning the elements of b to a slice of the elements in a.
For the slice shown, the elements selected from a are .
â€” end example]

#### 28.6.5.2 Assignment [slice.arr.assign]

```void operator=(const valarray<T>&) const; const slice_array& operator=(const slice_array&) const; ```
These assignment operators have reference semantics, assigning the values of the argument array elements to selected elements of the valarray<T> object to which the slice_array object refers.

#### 28.6.5.3 Compound assignment [slice.arr.comp.assign]

```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; ```
These compound assignments have reference semantics, applying the indicated operation to the elements of the argument array and selected elements of the valarray<T> object to which the slice_array object refers.

#### 28.6.5.4 Fill function [slice.arr.fill]

```void operator=(const T&) const; ```
This function has reference semantics, assigning the value of its argument to the elements of the valarray<T> object to which the slice_array object refers.