std::valarray::operator[]

 

C++

Language

Standard library headers

Concepts

Utilities library

Strings library

Containers library

Algorithms library

Iterators library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

 

Numerics library

Common mathematical functions

Floating-point environment

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Pseudo-random number generation

Compile-time rational arithmetic (C++11)

Generic numeric operations

iota (C++11)

accumulate

inner_product

adjacent_difference

partial_sum

 

std::valarray

Member functions
valarray::valarray valarray::~valarray valarray::operator= valarray::operator[] valarray::swap valarray::size valarray::resize valarray::sum valarray::min valarray::max valarray::shift valarray::cshift valarray::apply	valarray::operator+valarray::operator-valarray::operator~valarray::operator! valarray::operator+=valarray::operator-=valarray::operator*=valarray::operator/=valarray::operator%=valarray::operator&=valarray::operator|=valarray::operator^=valarray::operator<<=valarray::operator>>=
Non-member functions
swap (C++11) begin (C++11) end (C++11) abs exp log log10 pow sqrt sin cos tan asin acos atan atan2 sinh cosh tanh	operator*operator/operator%operator+operator-operator^operator&operator|operator<<operator>>operator&&operator|| operator==operator!=operator<operator>operator<=operator>=
Helper classes
slice_array gslice_array indirect_array	slice gslice mask_array

 

const T&            operator[]( size_t pos ) const;	(1)
T&                  operator[]( size_t pos );	(2)
valarray<T>         operator[]( slice slicearr ) const;	(3)
slice_array<T>      operator[]( slice slicearr );	(4)
valarray<T>         operator[]( const gslice& gslicearr ) const;	(5)
gslice_array<T>     operator[]( const gslice& gslicearr );	(6)
valarray<T>         operator[]( const valarray<bool>& boolarr ) const;	(7)
mask_array<T>       operator[]( const valarray<bool>& boolarr );	(8)
valarray<T>         operator[]( const valarray<size_t>& indarr ) const;	(9)
indirect_array<T>   operator[]( const valarray<size_t>& indarr );	(10)

Retrieve single elements or portions of the array.

The const overloads that return element sequences create a new std::valarray object. The non-const overloads return classes holding references to the array elements.

Return value

1,2) A reference to the corresponding element

3,5,7,9) A std::valarray object containing copies of the selected items

4,6,8,10) The corresponding data structure containing references to the selected items

Exceptions

(none)

Precondition

The selected elements must exist.

Notes

• For proper values of i and j, the following properties are true:

1) (a[i] = q, a[i]) == q

For a non-const a.

2) &a[i+j] == &a[i] + j

This means that valarray elements are adjacent in memory.

3) &a[i] != &b[j]

This holds for every objects a and b that are not aliases of one another.

This means that there are no aliases in the elements and this property can be used to perform some kinds of optimization.

• References become invalid on resize or when the array is destructed.