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std::filesystem::create_directory, std::filesystem::create_directories

Defined in header <filesystem> 
bool create_directory( const std::filesystem::path& p );
bool create_directory( const std::filesystem::path& p, std::error_code& ec );
 (1) (since C++17) 
bool create_directory( const std::filesystem::path& p,
                       const std::filesystem::path& existing_p );
bool create_directory( const std::filesystem::path& p,
                       const std::filesystem::path& existing_p,
                       std::error_code& ec );
 (2) (since C++17) 
bool create_directories( const std::filesystem::path& p );
bool create_directories( const std::filesystem::path& p,
                         std::error_code& ec );
 (3) (since C++17)
1) Creates the directory p as if by POSIX mkdir() with a second argument of static_cast<int>(std::filesystem::perms::all) (the parent directory must already exist). If p already exists and is already a directory, the function does nothing (this condition is not treated as an error).
2) Same as (1), except that the attributes of the new directory are copied from existing_p (which must be a directory that exists). It is OS-dependent which attributes are copied: on POSIX systems, the attributes are copied as if by 
stat(existing_p.c_str(), &attributes_stat)
mkdir(p.c_str(), attributes_stat.st_mode)
On Windows OS, the attributes are copied as if by 
CreateDirectoryExW(existing_p.c_str(), p.c_str(), 0)
3) Executes (1) for every element of p that does not already exist.

The non-throwing overloads return false if any error occurs.

Parameters

p - the path to the new directory to create
existing_p - the path to a directory to copy the attributes from
ec - out-parameter for error reporting in the non-throwing overload

Return value

1,2) true if directory creation is successful, false otherwise.

Exceptions

1,3) The overload that does not take a std::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 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. This overload has
noexcept specification:
noexcept
2) The overload that does not take a std::error_code& parameter throws filesystem_error on underlying OS API errors, constructed with p as the first argument, existing_p 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 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. This overload has
noexcept specification:
noexcept

Notes

The attribute-preserving overload (2) is implicitly invoked by copy() when recursively copying directories. Its equivalent in boost.filesystem is copy_directory (with argument order reversed).

Example

#include <iostream>
#include <fstream>
#include <cstdlib>
#include <filesystem>
namespace fs = std::filesystem;
 
int main()
{
    fs::create_directories("sandbox/1/2/a");
    fs::create_directory("sandbox/1/2/b");
    fs::permissions("sandbox/1/2/b", fs::perms::remove_perms | fs::perms::others_all);
    fs::create_directory("sandbox/1/2/c", "sandbox/1/2/b");
    std::system("ls -l sandbox/1/2");
    fs::remove_all("sandbox");
}

Possible output:

drwxr-xr-x 2 user group 4096 Apr 15 09:33 a
drwxr-x--- 2 user group 4096 Apr 15 09:33 b
drwxr-x--- 2 user group 4096 Apr 15 09:33 c

See also

(C++17)(C++17)
 creates a symbolic link
(function)
(C++17)
 copies files or directories
(function)
(C++17)
 identifies file system permissions
(enum)

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