I am trying to learn ranges in C 20 using Microsoft Visual Studio 2019.
I created a function to make lowercase in a string and replace all spaces by '_'.
template <typename R>
auto cpp20_string_to_lowercase_without_spaces( R&& rng )
{
auto view = rng
| std::ranges::views::transform( ::tolower )
| std::ranges::views::common;
std::ranges::replace( view, ' ', '_' );
return view;
}
And I got the following errors:
Error C2672 'operator __surrogate_func': no matching overloaded function found
Error C7602 'std::ranges::_Replace_fn::operator ()': the associated constraints are not satisfied
I tried to use view.begin(), view.end()
I tried to use the std::ranges::copy
before call std::ranges::replace.
Is it something I am doing wrong?
PS: In the project settings, I had to select Preview - Features from the Latest C Working Draft (/std:c latest)
because with ISO C 20 Standard (/std:c 20)
with the latest version of Visual Studio 2019 preview I can't use views without compilation errors.
CodePudding user response:
transform
creates a non-modifiable view. Specifically, it creates a range containing objects that are manufactured as needed. They have no permanent, fixed storage, so they cannot be "replaced" with something else.
You can copy the range into a container and then execute your replace operation on the container.