std::experimental::filesystem::absolute, std::experimental::filesystem::system_complete

 

C++

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Filesystem library (C++17)

Technical Specifications

 

Technical specifications

Filesystem library (filesystem TS)

Library fundamentals (library fundamentals TS)

Library fundamentals 2 (library fundamentals 2 TS)

Extensions for parallelism (parallelism TS)

Concepts (concepts TS)

Extensions for concurrency (concurrency TS)

Special mathematical functions (special math TR)

 

Filesystem library

Classes
filesystem::path filesystem::filesystem_error filesystem::directory_entry filesystem::directory_iterator filesystem::recursive_directory_iterator filesystem::file_status	filesystem::space_info filesystem::file_type filesystem::perms filesystem::copy_options filesystem::directory_options filesystem::file_time_type
Functions
filesystem::absolute filesystem::system_complete filesystem::canonical filesystem::copy filesystem::copy_file filesystem::copy_symlink filesystem::create_directory filesystem::create_directories filesystem::create_hard_link filesystem::create_symlink filesystem::create_directory_symlink filesystem::current_path filesystem::exists filesystem::equivalent	filesystem::file_size filesystem::hard_link_count filesystem::last_write_time filesystem::permissions filesystem::read_symlink filesystem::remove filesystem::remove_all filesystem::rename filesystem::resize_file filesystem::space filesystem::status filesystem::symlink_status filesystem::temp_directory_path
File types
filesystem::is_block_file filesystem::is_character_file filesystem::is_directory filesystem::is_empty filesystem::status_known	filesystem::is_fifo filesystem::is_other filesystem::is_regular_file filesystem::is_socket filesystem::is_symlink

 

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

1) Returns absolute path of p relative to base according to the following rules:

• If p has both root name and root directory (e.g. "C:\users", then the path is returned, unmodified.
• If p has a root name not followed by a root directory (e.g. "C:text.txt"), then base is inserted between p's root name and the remainder of p. Formally, p.root_name() / fs::absolute(base).root_directory() / fs::absolute(base).relative_path() / p.relative_path() is returned,
• If p has no root name, but has a root directory (e.g. "/var/tmp/file.txt" on a POSIX system or "\users\ABC\Document.doc" on Windows, then the root name of base, if it has one, is prepended to p (on a POSIX system, p is not modified, on a Windows system, "\users\ABC\Document.doc" becomes "C:\users\ABC\Document.doc". Formally, fs::absolute(base).root_name() / p is returned.
• If p has no root name and no root directory (e.g. "../file.txt", then the entire base is prepended to p. Formally, absolute(base) / p is returned.

2) Obtains the absolute path that identifies the file that the OS file opening API would access given the pathname p. On POSIX systems, this is equivalent to (1) with the default base (fs::current_path()). On Windows systems, each logical drive has its own current working directory, and so if p is not already absolute and has a root name component (e.g. "E:filename.txt", that drive's current working directory is used, which may have been set by an earlier executed program.

Parameters

p	-	path to convert to absolute form
base	-	path (not necessarily absolute) to serve as the starting location
ec	-	out-parameter for error reporting in the non-throwing overload

Return value

Returns an absolute (although not necessarily canonical) path formed by combining p and base as described above.

Exceptions

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:  

noexcept

  

Notes

On systems that support root names (e.g. Windows), the result of calling absolute on a relative path that has a root name (e.g. "D:file.txt" when the root name of base is different will usually result in a non-existent path.

Example

Run this code

#include <iostream>
#include <filesystem>
namespace fs = std::experimental::filesystem;
int main()
{
    fs::path p = "C:cl.exe";
    std::cout << "Current path is " << fs::current_path() << '\n'
              << "Absolute path for " << p << " is " << fs::absolute(p) << '\n'
	      << "System complete path for " << p << " is " << fs::system_complete(p) << '\n';
}

Possible output:

Current path is "D:/local/ConsoleApplication1"
Absolute path for "C:cl.exe" is "C:/local/ConsoleApplication1/cl.exe"
System complete path for "C:cl.exe" is "C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\bin\cl.exe"

See also

canonical	composes a canonical path (function)