std::begin(std::valarray)

 

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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
Deduction guides(C++17)

 

template< class T > /*unspecified1*/ begin( valarray<T>& v );	(1)	(since C++11)
template< class T > /*unspecified2*/ begin( const valarray<T>& v );	(2)	(since C++11)

The overload of std::begin for valarray returns an iterator of unspecified type referring to the first element in the numeric array.

1) The return type meets the requirements of mutable LegacyRandomAccessIterator.

2) The return type meets the requirements of constant LegacyRandomAccessIterator.

The iterator obtained from this function is invalidated when the member function resize() is called on the array v or when the lifetime of v ends, whichever comes first.

Parameters

v

-

a numeric array

Return value

Iterator to the first value in the numeric array.

Exceptions

May throw implementation-defined exceptions.

Notes

Unlike other functions that take std::valarray arguments, begin() cannot accept the replacement types (such as the types produced by expression templates) that may be returned from expressions involving valarrays: std::begin(v1 + v2) is not portable, std::begin(std::valarray<T>(v1 + v2)) has to be used instead.

The intent of this function is to allow range for loops to work with valarrays, not to provide container semantics.

Example

Run this code

#include <iostream>
#include <valarray>
#include <algorithm>
 
auto show = [](std::valarray<int> const& v) {
    std::for_each(std::begin(v), std::end(v), [](int c) {
        std::cout << c << ' ';
    });
    std::cout << '\n';
};
 
int main()
{
    const std::valarray<int> x { 47, 70, 37, 52, 90, 23, 17, 33, 22, 16, 21, 4 };
    const std::valarray<int> y { 25, 31, 71, 56, 21, 21, 15, 34, 21, 27, 12, 6 };
 
    show(x); 
    show(y); 
 
    const std::valarray<int> z { x + y };
 
    std::for_each(std::begin(z), std::end(z), [](char c) { std::cout << c; });
}

Output:

47 70 37 52 90 23 17 33 22 16 21 4 
25 31 71 56 21 21 15 34 21 27 12 6 
Hello, C++!

See also

std::end(std::valarray) (C++11)

specializes std::end (function template)