std::ranges::subrange<I,S,K>::operator PairLike

Since C++20
  1. Converts subrange to a pair-like type.

# Declarations

template< /*different-from*/<subrange> PairLike >
requires /*pair-like-convertible-from*/<PairLike, const I&, const S&>
constexpr operator PairLike() const;

(since C++20)

Helper concepts

template< class T >
concept /*pair-like*/ = /* see description */;

(exposition only*)

template< class T, class U, class V >
concept /*pair-like-convertible-from*/ = /* see description */;

(exposition only*)

# Return value

PairLike(begin_ ,end_ )

# Notes

Following types in the standard library are pair-like:

A program-defined type derived from one of these types can be a pair-like type, if

Since subrange specializations are range types, conversion to them are not performed via this conversion function.

std::array specializations cannot be converted from subrange, since they are range types.

# Example

#include <iostream>
#include <ranges>
#include <string>
#include <utility>
 
using striter = std::string::const_iterator;
 
using legacy_strview = std::pair<striter, striter>;
 
void legacy_print(legacy_strview p)
{
    for (; p.first != p.second; ++p.first)
        std::cout << *p.first << ' ';
    std::cout << '\n';
}
 
int main()
{
    std::string dat{"ABCDE"};
    for (auto v{std::ranges::subrange{dat}}; v; v = {v.begin(), v.end() - 1})
    {
        /*...*/
        legacy_print(legacy_strview{v});
    }
}

# See also