std::errc(3) C++ Standard Libary std::errc(3) NAME std::errc - std::errc Synopsis Defined in header <system_error> enum class errc; (since C++11) The scoped enumeration std::errc defines the values of portable error conditions that correspond to the POSIX error codes. Member constants Constant Equivalent POSIX Error address_family_not_supported EAFNOSUPPORT address_in_use EADDRINUSE address_not_available EADDRNOTAVAIL already_connected EISCONN argument_list_too_long E2BIG argument_out_of_domain EDOM bad_address EFAULT bad_file_descriptor EBADF bad_message EBADMSG broken_pipe EPIPE connection_aborted ECONNABORTED connection_already_in_progress EALREADY connection_refused ECONNREFUSED connection_reset ECONNRESET cross_device_link EXDEV destination_address_required EDESTADDRREQ device_or_resource_busy EBUSY directory_not_empty ENOTEMPTY executable_format_error ENOEXEC file_exists EEXIST file_too_large EFBIG filename_too_long ENAMETOOLONG function_not_supported ENOSYS host_unreachable EHOSTUNREACH identifier_removed EIDRM illegal_byte_sequence EILSEQ inappropriate_io_control_operation ENOTTY interrupted EINTR invalid_argument EINVAL invalid_seek ESPIPE io_error EIO is_a_directory EISDIR message_size EMSGSIZE network_down ENETDOWN network_reset ENETRESET network_unreachable ENETUNREACH no_buffer_space ENOBUFS no_child_process ECHILD no_link ENOLINK no_lock_available ENOLCK no_message_available (deprecated) ENODATA no_message ENOMSG no_protocol_option ENOPROTOOPT no_space_on_device ENOSPC no_stream_resources (deprecated) ENOSR no_such_device_or_address ENXIO no_such_device ENODEV no_such_file_or_directory ENOENT no_such_process ESRCH not_a_directory ENOTDIR not_a_socket ENOTSOCK not_a_stream (deprecated) ENOSTR not_connected ENOTCONN not_enough_memory ENOMEM not_supported ENOTSUP operation_canceled ECANCELED operation_in_progress EINPROGRESS operation_not_permitted EPERM operation_not_supported EOPNOTSUPP operation_would_block EWOULDBLOCK owner_dead EOWNERDEAD permission_denied EACCES protocol_error EPROTO protocol_not_supported EPROTONOSUPPORT read_only_file_system EROFS resource_deadlock_would_occur EDEADLK resource_unavailable_try_again EAGAIN result_out_of_range ERANGE state_not_recoverable ENOTRECOVERABLE stream_timeout (deprecated) ETIME text_file_busy ETXTBSY timed_out ETIMEDOUT too_many_files_open_in_system ENFILE too_many_files_open EMFILE too_many_links EMLINK too_many_symbolic_link_levels ELOOP value_too_large EOVERFLOW wrong_protocol_type EPROTOTYPE Non-member functions make_error_code(std::errc) creates error code value for errc enum e (C++11) (function) make_error_condition(std::errc) creates an error condition for an errc value e (C++11) (function) Helper classes extends the type trait is_error_condition_enum<std::errc> std::is_error_condition_enum to iden- tify errc (C++11) values as error conditions (function template) Example // Run this code #include <filesystem> #include <fstream> #include <iomanip> #include <iostream> #include <string> #include <system_error> #include <thread> void print_error(const std::string& details, std::error_code error_code) { std::string value_name; if (error_code == std::errc::invalid_argument) value_name = "std::errc::invalid_argument"; if (error_code == std::errc::no_such_file_or_directory) value_name = "std::errc::no_such_file_or_directory"; if (error_code == std::errc::is_a_directory) value_name = "std::errc::is_a_directory"; if (error_code == std::errc::permission_denied) value_name = "std::errc::permission_denied"; std::cout << details << ":\n " << std::quoted(error_code.message()) << " (" << value_name << ")\n\n"; } void print_errno(const std::string& details, int errno_value = errno) { print_error(details, std::make_error_code(std::errc(errno_value))); } int main() { std::cout << "Detaching a not-a-thread...\n"; try { std::thread().detach(); } catch (const std::system_error& e) { print_error("Error detaching empty thread", e.code()); } std::cout << "Opening nonexistent file...\n"; std::ifstream nofile{"nonexistent-file"}; if (!nofile.is_open()) print_errno("Error opening nonexistent file for reading"); std::cout << "Reading from directory as a file...\n"; std::filesystem::create_directory("dir"); std::ifstream dir_stream{"dir"}; [[maybe_unused]] char c = dir_stream.get(); if (!dir_stream.good()) print_errno("Error reading data from directory"); std::cout << "Open read-only file for writing...\n"; std::fstream{"readonly-file", std::ios::out}; std::filesystem::permissions("readonly-file", std::filesys- tem::perms::owner_read); std::fstream write_readonly("readonly-file", std::ios::out); if (!write_readonly.is_open()) print_errno("Error opening read-only file for writing"); } Possible output: Detaching a not-a-thread... Error detaching empty thread: "Invalid argument" (std::errc::invalid_argument) Opening nonexistent file... Error opening nonexistent file for reading: "No such file or directory" (std::errc::no_such_file_or_directory) Reading from directory as a file... Error reading data from directory: "Is a directory" (std::errc::is_a_directory) Open read-only file for writing... Error opening read-only file for writing: "Permission denied" (std::errc::permission_denied) Defect reports The following behavior-changing defect reports were applied retroac- tively to previously published C++ standards. DR Applied to Behavior as published Cor- rect behavior the member constants no_message_available, LWG 3869 C++11 no_stream_resources, not_a_stream and dep- recated them stream_timeout referred to the obsolete POSIX STREAMS API^[1] 1. a Although the corresponding POSIX error numbers ENODATA, ENOSR, ENOSTR and ETIME were marked "obsolescent" in POSIX 2017, the STREAMS API was optional and not required for conformance to the previous POSIX standard (because popular unix-like systems refused to implement it). See also error_code holds a platform-dependent error code (C++11) (class) error_condition holds a portable error code (C++11) (class) http://cppreference.com 2024.06.10 std::errc(3)
NAME | Synopsis | Member constants | Non-member functions | Helper classes | Example | Possible output: | See also
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