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std::end(std::valarray)

From cppreference.com
< cpp‎ | numeric‎ | valarray
 
 
 
 
template< class T >
/* see below */ end( valarray<T>& v );
(1) (since C++11)
template< class T >
/* see below */ end( const valarray<T>& v );
(2) (since C++11)

The overload of std::end for valarray returns an iterator of unspecified type referring to the one past the last element in the numeric array.

1) The return type must
(since C++20)
  • have a member type value_type, which is T, and
  • have a member type reference, which is T&.
2) The return type must
(since C++20)
  • have a member type value_type, which is T, and
  • have a member type reference, which is const T&.

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

Contents

[edit] Parameters

v - a numeric array

[edit] Return value

Iterator to one past the last value in the numeric array.

[edit] Exceptions

May throw implementation-defined exceptions.

[edit] Notes

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

[edit] Example

#include <algorithm>
#include <iostream>
#include <valarray>
 
int main()
{
    const std::valarray<char> va
    {
        'H', 'e', 'l', 'l', 'o', 
        ',', ' ', 
        'C', '+', '+', '!', '\n'
    };
 
    std::for_each(std::begin(va), std::end(va),
                  [](char c){ std::cout << c; });
}

Output:

Hello, C++!

[edit] Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR Applied to Behavior as published Correct behavior
LWG 2058 C++11 1. end() was required to support replacement types
2. it was unspecified when the returned iterators will be invalidated
1. not required
2. specified

[edit] See also

overloads std::begin
(function template) [edit]