std::experimental::filesystem:: exists
From cppreference.com
<
cpp
|
experimental
|
fs
Defined in header
<experimental/filesystem>
|
||
bool
exists
(
file_status s
)
|
(1) | (filesystem TS) |
bool
exists
(
const
path
&
p
)
;
bool exists ( const path & p, error_code & ec ) |
(2) | (filesystem TS) |
Checks if the given file status or path corresponds to an existing file or directory.
1)
Equivalent to
status_known
(
s
)
&&
s.
type
(
)
!
=
file_type
::
not_found
.
2)
Equivalent to
exists
(
status
(
p
)
)
or
exists
(
status
(
p, ec
)
)
(symlinks are followed). The non-throwing overload returns
false
if an error occurs.
Parameters
s | - | file status to check |
p | - | path to examine |
ec | - | out-parameter for error reporting in the non-throwing overload |
Return value
true if the given path or file status corresponds to an existing file or directory, false otherwise.
Exceptions
1)
noexcept
specification:
noexcept
2)
The overload that does not take an
error_code
&
parameter throws
filesystem_error
on underlying OS API errors, constructed with
p
as the first argument and the OS error code as the error code argument.
std::
bad_alloc
may be thrown if memory allocation fails. The overload taking an
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
The information provided by this function is usually also provided as a byproduct of directory iteration. During directory iteration, calling
exists(*iterator)
is less efficient than
exists(iterator->status())
.
Example
Run this code
#include <cstdint> #include <experimental/filesystem> #include <fstream> #include <iostream> namespace fs = std::experimental::filesystem; void demo_exists(const fs::path& p, fs::file_status s = fs::file_status{}) { std::cout << p; if (fs::status_known(s) ? fs::exists(s) : fs::exists(p)) std::cout << " exists\n"; else std::cout << " does not exist\n"; } int main() { fs::create_directory("sandbox"); std::ofstream("sandbox/file"); // create regular file fs::create_symlink("non-existing", "sandbox/symlink"); demo_exists("sandbox"); for (auto it = fs::directory_iterator("sandbox"); it != fs::directory_iterator(); ++it) demo_exists(*it, it->status()); // use cached status from directory entry fs::remove_all("sandbox"); }
Output:
"sandbox" exists "sandbox/file" exists "sandbox/symlink" does not exist
See also
determines file attributes
determines file attributes, checking the symlink target (function) |
|
represents file type and permissions
(class) |
|
cached status of the file designated by this directory entry
cached symlink_status of the file designated by this directory entry (public member function of
std::experimental::filesystem::directory_entry
)
|