5.0 KiB
[template.indirect.array]
29 Numerics library [numerics]
29.6 Numeric arrays [numarray]
29.6.9 Class template indirect_array [template.indirect.array]
29.6.9.1 Overview [template.indirect.array.overview]
namespace std {template class indirect_array {public:using value_type = T; void operator= (const valarray&) const; void operator*= (const valarray&) const; void operator/= (const valarray&) const; void operator%= (const valarray&) const; void operator+= (const valarray&) const; void operator-= (const valarray&) const; void operator^= (const valarray&) const; void operator&= (const valarray&) const; void operator|= (const valarray&) const; void operator<<=(const valarray&) const; void operator>>=(const valarray&) const;
indirect_array(const indirect_array&); ~indirect_array(); const indirect_array& operator=(const indirect_array&) const; void operator=(const T&) const;
indirect_array() = delete; // as implied by declaring copy constructor above};}
This template is a helper template used by the indirect subscript operator
indirect_array<T> valarray<T>::operator[](const valarray<size_t>&);
It has reference semantics to a subset of an array specified by anindirect_array.
Thus, the expressiona[indirect] = b; has the effect of assigning the elements ofb to the elements ina whose indices appear inindirect.
29.6.9.2 Assignment [indirect.array.assign]
void operator=(const valarray<T>&) const; const indirect_array& operator=(const indirect_array&) const;
These assignment operators have reference semantics, assigning the values of the argument array elements to selected elements of thevalarray object to which it refers.
If theindirect_array specifies an element in thevalarray object to which it refers more than once, the behavior is undefined.
[Example 1:
int addr[] = {2, 3, 1, 4, 4}; valarray<size_t> indirect(addr, 5); valarray a(0., 10), b(1., 5); a[indirect] = b; results in undefined behavior since element 4 is specified twice in the indirection.
â end example]
29.6.9.3 Compound assignment [indirect.array.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 thevalarray object to which theindirect_array object refers.
If theindirect_array specifies an element in thevalarray object to which it refers more than once, the behavior is undefined.
29.6.9.4 Fill function [indirect.array.fill]
void operator=(const T&) const;
This function has reference semantics, assigning the value of its argument to the elements of thevalarray object to which theindirect_array object refers.