I am getting compilation erorr while trying to zip two vectors and apply and filter as below.
#include <range/v3/all.hpp>
int main()
{
std::vector v1 = {0, 1, 2, 3, 4};
std::vector v2 = {'a', 'b', 'c', 'd', 'e'};
auto pred = [](auto& p) { return (p.first != 0); };
auto x = ranges::views::zip(v1, v2);
auto y = x | ranges::views::filter(pred);
}
Here is compilation error
<source>: In function 'int main()':
<source>:15:16: error: no match for 'operator|' (operand types are 'ranges::zip_view<ranges::ref_view<std::vector<int, std::allocator<int> > >, ranges::ref_view<std::vector<char, std::allocator<char> > > >' and 'ranges::views::view_closure<ranges::detail::bind_back_fn_<ranges::views::filter_base_fn, main()::<lambda(auto:28&)> > >')
15 | auto y = x | ranges::views::filter(pred);
| ~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~
| | |
| | ranges::views::view_closure<ranges::detail::bind_back_fn_<ranges::views::filter_base_fn, main()::<lambda(auto:28&)> > >
| ranges::zip_view<ranges::ref_view<std::vector<int, std::allocator<int> > >, ranges::ref_view<std::vector<char, std::allocator<char> > > >
In file included from /opt/compiler-explorer/gcc-13.2.0/include/c++/13.2.0/regex:40,
from /opt/compiler-explorer/libs/rangesv3/0.12.0/include/range/v3/view/tokenize.hpp:18,
from /opt/compiler-explorer/libs/rangesv3/0.12.0/include/range/v3/view.hpp:81,
from /opt/compiler-explorer/libs/rangesv3/0.12.0/include/range/v3/all.hpp:25,
from <source>:4:
You'll need a const& in your pred:
auto pred = [](auto const& p) { return p.first != 0; };
This can also be achieved by using a forwarding reference:
auto pred = [](auto&& p) { return p.first != 0; };