cppreference的std::errc: std::errc - cppreference.com

对应定义(come from: 2022\Community\VC\Tools\MSVC\14.33.31629\include\xerrc.h)

enum class errc { // names for generic error codesaddress_family_not_supported       = 102, // EAFNOSUPPORTaddress_in_use                     = 100, // EADDRINUSEaddress_not_available              = 101, // EADDRNOTAVAILalready_connected                  = 113, // EISCONNargument_list_too_long             = 7, // E2BIGargument_out_of_domain             = 33, // EDOMbad_address                        = 14, // EFAULTbad_file_descriptor                = 9, // EBADFbad_message                        = 104, // EBADMSGbroken_pipe                        = 32, // EPIPEconnection_aborted                 = 106, // ECONNABORTEDconnection_already_in_progress     = 103, // EALREADYconnection_refused                 = 107, // ECONNREFUSEDconnection_reset                   = 108, // ECONNRESETcross_device_link                  = 18, // EXDEVdestination_address_required       = 109, // EDESTADDRREQdevice_or_resource_busy            = 16, // EBUSYdirectory_not_empty                = 41, // ENOTEMPTYexecutable_format_error            = 8, // ENOEXECfile_exists                        = 17, // EEXISTfile_too_large                     = 27, // EFBIGfilename_too_long                  = 38, // ENAMETOOLONGfunction_not_supported             = 40, // ENOSYShost_unreachable                   = 110, // EHOSTUNREACHidentifier_removed                 = 111, // EIDRMillegal_byte_sequence              = 42, // EILSEQinappropriate_io_control_operation = 25, // ENOTTYinterrupted                        = 4, // EINTRinvalid_argument                   = 22, // EINVALinvalid_seek                       = 29, // ESPIPEio_error                           = 5, // EIOis_a_directory                     = 21, // EISDIRmessage_size                       = 115, // EMSGSIZEnetwork_down                       = 116, // ENETDOWNnetwork_reset                      = 117, // ENETRESETnetwork_unreachable                = 118, // ENETUNREACHno_buffer_space                    = 119, // ENOBUFSno_child_process                   = 10, // ECHILDno_link                            = 121, // ENOLINKno_lock_available                  = 39, // ENOLCKno_message_available               = 120, // ENODATAno_message                         = 122, // ENOMSGno_protocol_option                 = 123, // ENOPROTOOPTno_space_on_device                 = 28, // ENOSPCno_stream_resources                = 124, // ENOSRno_such_device_or_address          = 6, // ENXIOno_such_device                     = 19, // ENODEVno_such_file_or_directory          = 2, // ENOENTno_such_process                    = 3, // ESRCHnot_a_directory                    = 20, // ENOTDIRnot_a_socket                       = 128, // ENOTSOCKnot_a_stream                       = 125, // ENOSTRnot_connected                      = 126, // ENOTCONNnot_enough_memory                  = 12, // ENOMEMnot_supported                      = 129, // ENOTSUPoperation_canceled                 = 105, // ECANCELEDoperation_in_progress              = 112, // EINPROGRESSoperation_not_permitted            = 1, // EPERMoperation_not_supported            = 130, // EOPNOTSUPPoperation_would_block              = 140, // EWOULDBLOCKowner_dead                         = 133, // EOWNERDEADpermission_denied                  = 13, // EACCESprotocol_error                     = 134, // EPROTOprotocol_not_supported             = 135, // EPROTONOSUPPORTread_only_file_system              = 30, // EROFSresource_deadlock_would_occur      = 36, // EDEADLKresource_unavailable_try_again     = 11, // EAGAINresult_out_of_range                = 34, // ERANGEstate_not_recoverable              = 127, // ENOTRECOVERABLEstream_timeout                     = 137, // ETIMEtext_file_busy                     = 139, // ETXTBSYtimed_out                          = 138, // ETIMEDOUTtoo_many_files_open_in_system      = 23, // ENFILEtoo_many_files_open                = 24, // EMFILEtoo_many_links                     = 31, // EMLINKtoo_many_symbolic_link_levels      = 114, // ELOOPvalue_too_large                    = 132, // EOVERFLOWwrong_protocol_type                = 136 // EPROTOTYPE
};

示例代码:

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 << "), " << error_code<< " \n";
}void print_errno(const std::string& details, int errno_value = errno)
{print_error(details, std::make_error_code(std::errc(errno_value)));
}void testMain()
{// Detaching a not-a-threadtry{std::thread().detach();}catch (const std::system_error& e){print_error("Error detaching empty thread", e.code());}// Opening nonexistent file{std::ifstream nofile("nonexistent-file");if (!nofile.is_open()){print_errno("Error opening nonexistent file for reading");}}// Reading from directory as a file{std::filesystem::create_directory("testDir");std::ifstream         dir_stream("testDir");[[maybe_unused]] char c = dir_stream.get();if (!dir_stream.good()){print_errno("Error reading data from directory");}}// Open readonly file for writing{{std::fstream new_file("readonly-file", std::ios::out);}std::filesystem::permissions("readonly-file", std::filesystem::perms::owner_read);std::fstream write_readonly("readonly-file", std::ios::out);if (!write_readonly.is_open()){print_errno("Error opening readonly file for writing");}}
}

运行程序之后的输出:

Error detaching empty thread:"invalid argument" (std::errc::invalid_argument), generic:22
Error opening nonexistent file for reading:"no such file or directory" (std::errc::no_such_file_or_directory), generic:2
Error reading data from directory:"permission denied" (std::errc::permission_denied), generic:13
Error opening readonly file for writing:"permission denied" (std::errc::permission_denied), generic:13