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std::experi..._block_file(3) C++ Standard Libary std::experi..._block_file(3) NAME std::experimental::filesystem::is_block_file - std::experimen- tal::filesystem::is_block_file Synopsis Defined in header <experimental/filesystem> bool is_block_file( file_status s ); (1) (filesystem TS) bool is_block_file( const path& p ); (2) (filesystem TS) bool is_block_file( const path& p, error_code& ec ) noexcept; Checks if the given file status or path corresponds to a block spe- cial file, as if determined by the POSIX S_ISBLK . Examples of block special files are block devices such as /dev/sda or /dev/loop0 on Linux. 1) Equivalent to s.type() == file_type::block. 2) Equivalent to is_block_file(status(p)) or is_block_file(status(p, ec)). 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 file indicated by p or if the type indicated s refers to a block device. The non-throwing overload returns false if an error occurs. Exceptions 1) noexcept specification: noexcept 2,3) The overload that does not take a error_code& parameter throws filesystem_error on underlying OS API errors, constructed with p as the first argu- ment 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 The information provided by this function is usually also provided as a byproduct of directory iteration. During directory iteration, calling is_block_file(*iterator) is less efficient than is_block_file(iterator->status()) Example // Run this code #include <iostream> #include <fstream> #include <cstdio> #include <cstring> #include <experimental/filesystem> #include <unistd.h> #include <sys/socket.h> #include <sys/un.h> #include <sys/stat.h> namespace fs = std::experimental::filesystem; void demo_status(const fs::path& p, fs::file_status s) { std::cout << p; // alternative: switch(s.type()) { case fs::file_type::regular: ...} if(fs::is_regular_file(s)) std::cout << " is a regular file\n"; if(fs::is_directory(s)) std::cout << " is a directory\n"; if(fs::is_block_file(s)) std::cout << " is a block device\n"; if(fs::is_character_file(s)) std::cout << " is a character de- vice\n"; if(fs::is_fifo(s)) std::cout << " is a named IPC pipe\n"; if(fs::is_socket(s)) std::cout << " is a named IPC socket\n"; if(fs::is_symlink(s)) std::cout << " is a symlink\n"; if(!fs::exists(s)) std::cout << " does not exist\n"; } int main() { // create files of different kinds fs::create_directory("sandbox"); std::ofstream("sandbox/file"); // create regular file fs::create_directory("sandbox/dir"); mkfifo("sandbox/pipe", 0644); struct sockaddr_un addr; addr.sun_family = AF_UNIX; std::strcpy(addr.sun_path, "sandbox/sock"); int fd = socket(PF_UNIX, SOCK_STREAM, 0); bind(fd, (struct sockaddr*)&addr, sizeof addr); fs::create_symlink("file", "sandbox/symlink"); // demo different status accessors for(auto it = fs::directory_iterator("sandbox"); it != fs::direc- tory_iterator(); ++it) demo_status(*it, it->symlink_status()); // use cached status from directory entry demo_status("dev/null", fs::status("/dev/null")); // direct calls to status demo_status("dev/sda", fs::status("/dev/sda")); demo_status("sandbox/no", fs::status("/sandbox/no")); // cleanup close(fd); fs::remove_all("sandbox"); } Possible output: "sandbox/file" is a regular file "sandbox/dir" is a directory "sandbox/pipe" is a named IPC pipe "sandbox/sock" is a named IPC socket "sandbox/symlink" is a symlink "dev/null" is a character device "dev/sda" is a block device "sandbox/no" does not exist See also status determines file attributes symlink_status determines file attributes, checking the symlink target (function) file_status represents file type and permissions (class) status_known checks whether file status is known (function) is_character_file checks whether the given path refers to a charac- ter device (function) is_directory checks whether the given path refers to a direc- tory (function) is_fifo checks whether the given path refers to a named pipe (function) is_other checks whether the argument refers to an other file (function) is_regular_file checks whether the argument refers to a regular file (function) is_socket checks whether the argument refers to a named IPC socket (function) is_symlink checks whether the argument refers to a symbolic link (function) exists checks whether path refers to existing file system object (function) cached status of the file designated by this di- rectory entry status cached symlink_status of the file designated by this directory symlink_status entry (public member function of std::experimental::filesystem::directory_entry) http://cppreference.com 2022.07.31 std::experi..._block_file(3)
NAME | Synopsis | Parameters | Return value | Exceptions | Notes | Example | Possible output: | See also
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