std::filesystem::directory_entry::is_character_file - cppreference.com (original) (raw)
| bool is_character_file() const; | (1) | (since C++17) |
|---|---|---|
| bool is_character_file( std::error_code& ec ) const noexcept; | (2) | (since C++17) |
Checks whether the pointed-to object is a character device. Effectively returns:
[edit] Parameters
| ec | - | out-parameter for error reporting in the non-throwing overload |
|---|
[edit] Return value
true if the referred-to filesystem object is a character device, false otherwise.
[edit] Exceptions
Any overload not marked noexcept may throw std::bad_alloc if memory allocation fails.
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.
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.
[edit] Example
#include
#include
#include
#include
#include
#include
#include
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/un.h>
#include <unistd.h>
namespace fs = std::filesystem;
void print_entry_type(const std::filesystem::directory_entry& entry)
{
std::cout << entry.path() << ": ";
if (!entry.exists())
std::cout << "does not exist ";
if (entry.is_block_file())
std::cout << "is a block device ";
if (entry.is_character_file())
std::cout << "is a character device ";
if (entry.is_directory())
std::cout << "is a directory ";
if (entry.is_fifo())
std::cout << "is a named IPC pipe ";
if (entry.is_regular_file())
std::cout << "is a regular file ";
if (entry.is_socket())
std::cout << "is a named IPC socket ";
if (entry.is_symlink())
std::cout << "(a symlink)";
if (entry.is_other())
std::cout << "(an other file)";
std::cout << '\n';
}
template<typename Type, typename Fun>
class scoped_cleanup
{
std::unique_ptr<Type, std::function<void(const Type*)>> u;
public:
scoped_cleanup(Type* ptr, Fun fun) : u{ptr, std::move(fun)} {}
};
int main()
{
// Create files of different kinds.
std::filesystem::current_path(fs::temp_directory_path());
const std::filesystem::path sandbox{"sandbox"};
scoped_cleanup remove_all_at_exit{&sandbox, [](const fs::path* p)
{
std::cout << "cleanup: remove_all(" << p << ")\n";
fs::remove_all(*p);
}};
std::filesystem::create_directory(sandbox);
std::ofstream{sandbox/"file"}; // Creates a regular file
std::filesystem::create_directory(sandbox/"dir");
mkfifo((sandbox/"pipe").string().data(), 0644);
struct sockaddr_un addr; addr.sun_family = AF_UNIX;
std::strcpy(addr.sun_path, (sandbox/"sock").string().data());
int fd{socket(PF_UNIX, SOCK_STREAM, 0)};
scoped_cleanup close_socket_at_exit{&fd, [](const int* f)
{
std::cout << "cleanup: close socket #" << *f << '\n';
close(*f);
}};
bind(fd, reinterpret_cast<sockaddr*>(std::addressof(addr)), sizeof addr);
fs::create_symlink("file", sandbox/"symlink");
for (std::filesystem::directory_entry entry: fs::directory_iterator(sandbox))
print_entry_type(entry);
// Request file system objects status directly:
for (const char str : {"/dev/null", "/dev/cpu", "/usr/include/c++",
"/usr/include/asm", "/usr/include/time.h"})
print_entry_type(fs::directory_entry{str});
} // Cleanup via scoped_cleanup objects
Possible output:
"sandbox/symlink": is a regular file (a symlink)
"sandbox/sock": is a named IPC socket (an other file)
"sandbox/pipe": is a named IPC pipe (an other file)
"sandbox/dir": is a directory
"sandbox/file": is a regular file
"/dev/null": is a character device (an other file)
"/dev/cpu": does not exist
"/usr/include/c++": is a directory
"/usr/include/asm": is a directory (a symlink)
"/usr/include/time.h": is a regular file
cleanup: close socket #3
cleanup: remove_all("sandbox")