void replace_filename( const std::filesystem::path& p ); void replace_filename( const std::filesystem::path& p, std::error_code& ec );  |  (since C++17) | 
Changes the filename of the directory entry.
Effectively modifies the path member by path.replace_filename(p) and calls refresh to update the cached attributes. If an error occurs, the values of the cached attributes are unspecified.
This function does not commit any changes to the filesystem.
| p | - | the path to append to the parent path of the currently stored path | 
| ec | - | out-parameter for error reporting in the non-throwing overload | 
(none).
The overload that does not take a std::error_code& parameter throws filesystem::filesystem_error on underlying OS API errors, constructed with p as the first path argument and the OS error code as the error code argument. The overload taking a std::error_code& parameter sets it to the OS API error code if an OS API call fails, and executes ec.clear() if no errors occur. Any overload not marked noexcept may throw std::bad_alloc if memory allocation fails.
#include <iostream>
#include <filesystem>
 
int main()
{
    namespace fs = std::filesystem;
    {
        fs::directory_entry entry{ "omega" };
        std::cout << entry << '\n';
        entry.replace_filename("alpha");
        std::cout << entry << '\n';
    }{
        fs::directory_entry entry{ "/omega/" };
        std::cout << entry << '\n';
        entry.replace_filename("alpha");
        std::cout << entry << '\n';
    }
}Output:
"omega" "alpha" "/omega/" "/omega/alpha"
|  assigns contents  (public member function)  | 
|
|  replaces the last path component with another path  (public member function of std::filesystem::path)   | 
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    https://en.cppreference.com/w/cpp/filesystem/directory_entry/replace_filename