std::experimental::filesystem::canonical (3) - Linux Manuals

std::experimental::filesystem::canonical: std::experimental::filesystem::canonical


std::experimental::filesystem::canonical - std::experimental::filesystem::canonical


Defined in header <experimental/filesystem>
path canonical( const path& p, const path& base = current_path() ); (1) (filesystem TS)
path canonical( const path& p, error_code& ec ); (2) (filesystem TS)
path canonical( const path& p, const path& base, error_code& ec ); (3) (filesystem TS)

Converts path p to a canonical absolute path, i.e. an absolute path that has no dot, dot-dot elements or symbolic links.
If p is not an absolute path, the function behaves as if it is first made absolute by absolute(p, base) or absolute(p) for (2)
The path p must exist.


p - a path which may be absolute or relative to base, and which must be an existing path
base - base path to be used in case p is relative
ec - error code to store error status to

Return value

An absolute path that resolves to the same file as absolute(p, base) (or absolute(p) for (2)).


The overload that does not take a error_code& parameter throws filesystem_error on underlying OS API errors, constructed with p as the first argument, base as the second argument, and the OS error code as the error code argument. std::bad_alloc may be thrown if memory allocation fails. The overload taking a 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. This overload has
noexcept specification:
This function is modeled after the POSIX realpath.


// Run this code

  #include <iostream>
  #include <experimental/filesystem>
  namespace fs = std::experimental::filesystem;
  int main()
      fs::path p = fs::path("..") / ".." / "AppData";
      std::cout << "Current path is " << fs::current_path() << '\n'
                << "Canonical path for " << p << " is " << fs::canonical(p) << '\n';

Possible output:

  Current path is "C:\Users\abcdef\AppData\Local\Temp"
  Canonical path for "..\..\AppData" is "C:\Users\abcdef\AppData"

See also

                represents a path
path (class)
                composes an absolute path
absolute converts a path to an absolute path replicating OS-specific behavior
system_complete (function)