std::filesystem:: absolute

From cppreference.com
Defined in header <filesystem>
path absolute ( const std:: filesystem :: path & p ) ;
(1) (since C++17)
path absolute ( const std:: filesystem :: path & p, std:: error_code & ec ) ;
(2) (since C++17)

Returns a path referencing the same file system location as p , for which filesystem::path::is_absolute() is true .

2) This non-throwing overload returns default-constructed path if an error occurs.

Parameters

p - path to convert to absolute form
ec - out-parameter for error reporting in the non-throwing overload

Return value

Returns an absolute (although not necessarily canonical) pathname referencing the same file as p .

Exceptions

Any overload not marked noexcept may throw std::bad_alloc if memory allocation fails.

1) Throws std::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.
2) Sets a std:: error_code & parameter to the OS API error code if an OS API call fails, and executes ec. clear ( ) if no errors occur.

Notes

Implementations are encouraged to not consider p not existing to be an error.

For POSIX-based operating systems, std :: filesystem :: absolute ( p ) is equivalent to std:: filesystem :: current_path ( ) / p except for when p is the empty path.

For Windows, std::filesystem::absolute may be implemented as a call to GetFullPathNameW .

Example

#include <filesystem>
#include <iostream>
namespace fs = std::filesystem;
 
int main()
{
    std::filesystem::path p = "foo.c";
    std::cout << "Current path is " << std::filesystem::current_path() << '\n';
    std::cout << "Absolute path for " << p << " is " << fs::absolute(p) << '\n';
}

Possible output:

Current path is "/tmp/1666297965.0051296"
Absolute path for "foo.c" is "/tmp/1666297965.0051296/foo.c"

See also

composes a canonical path
(function)
composes a relative path
(function)