错误号

在 <cerrno> 中定义的每个宏都扩展为类型为 int 的整型常量表达式，每个都具有正值，与大多数 POSIX 错误代码相匹配。定义了以下常量（实现可以定义更多，只要它们以 'E' 后跟数字或大写字母开头）。

在头文件 `<cerrno>` 中定义
E2BIG (C++11)	参数列表过长 (宏常量)
EACCES (C++11)	权限被拒绝 (宏常量)
EADDRINUSE (C++11)	地址正在使用中 (宏常量)
EADDRNOTAVAIL (C++11)	地址不可用 (宏常量)
EAFNOSUPPORT (C++11)	地址族不受支持 (宏常量)
EAGAIN (C++11)	资源不可用，请重试 (宏常量)
EALREADY (C++11)	连接已在进行中 (宏常量)
EBADF (C++11)	无效的文件描述符 (宏常量)
EBADMSG (C++11)	无效的消息 (宏常量)
EBUSY (C++11)	设备或资源忙 (宏常量)
ECANCELED (C++11)	操作已取消 (宏常量)
ECHILD (C++11)	没有子进程 (宏常量)
ECONNABORTED (C++11)	连接已中止 (宏常量)
ECONNREFUSED (C++11)	连接被拒绝 (宏常量)
ECONNRESET (C++11)	连接重置 (宏常量)
EDEADLK (C++11)	将发生资源死锁 (宏常量)
EDESTADDRREQ (C++11)	需要目标地址 (宏常量)
EDOM	数学参数超出函数域 (宏常量)
EEXIST (C++11)	文件已存在 (宏常量)
EFAULT (C++11)	无效地址 (宏常量)
EFBIG (C++11)	文件太大 (宏常量)
EHOSTUNREACH (C++11)	主机不可达 (宏常量)
EIDRM (C++11)	标识符已删除 (宏常量)
EILSEQ (C++11)	非法字节序列 (宏常量)
EINPROGRESS (C++11)	操作正在进行中 (宏常量)
EINTR (C++11)	中断函数 (宏常量)
EINVAL (C++11)	无效参数 (宏常量)
EIO (C++11)	I/O 错误 (宏常量)
EISCONN (C++11)	套接字已连接 (宏常量)
EISDIR (C++11)	是目录 (宏常量)
ELOOP (C++11)	符号链接级别过多 (宏常量)
EMFILE (C++11)	文件描述符值过大 (宏常量)
EMLINK (C++11)	链接过多 (宏常量)
EMSGSIZE (C++11)	消息过大 (宏常量)
ENAMETOOLONG (C++11)	文件名过长 (宏常量)
ENETDOWN (C++11)	网络已断开 (宏常量)
ENETRESET (C++11)	连接被网络中止 (宏常量)
ENETUNREACH (C++11)	网络不可达 (宏常量)
ENFILE (C++11)	系统中打开的文件过多 (宏常量)
ENOBUFS (C++11)	没有可用的缓冲区空间 (宏常量)
ENODATA (C++11)	STREAM 头读取队列中没有可用消息 (宏常量)
ENODEV (C++11)	没有这样的设备 (宏常量)
ENOENT (C++11)	没有这样的文件或目录 (宏常量)
ENOEXEC (C++11)	可执行文件格式错误 (宏常量)
ENOLCK (C++11)	没有可用的锁 (宏常量)
ENOLINK (C++11)	链接已断开 (宏常量)
ENOMEM (C++11)	空间不足 (宏常量)
ENOMSG (C++11)	没有所需类型的消息 (宏常量)
ENOPROTOOPT (C++11)	协议不可用 (宏常量)
ENOSPC (C++11)	设备上没有剩余空间 (宏常量)
ENOSR (C++11)	没有 STREAM 资源 (宏常量)
ENOSTR (C++11)	不是 STREAM (宏常量)
ENOSYS (C++11)	不支持该函数 (宏常量)
ENOTCONN (C++11)	套接字未连接 (宏常量)
ENOTDIR (C++11)	不是目录 (宏常量)
ENOTEMPTY (C++11)	目录不为空 (宏常量)
ENOTRECOVERABLE (C++11)	状态不可恢复 (宏常量)
ENOTSOCK (C++11)	不是套接字 (宏常量)
ENOTSUP (C++11)	不支持 (宏常量)
ENOTTY (C++11)	不适当的 I/O 控制操作 (宏常量)
ENXIO (C++11)	没有这样的设备或地址 (宏常量)
EOPNOTSUPP (C++11)	套接字不支持此操作 (宏常量)
EOVERFLOW (C++11)	值过大，无法存储在数据类型中 (宏常量)
EOWNERDEAD (C++11)	前一个所有者已死亡 (宏常量)
EPERM (C++11)	操作不被允许 (宏常量)
EPIPE (C++11)	管道破裂 (宏常量)
EPROTO (C++11)	协议错误 (宏常量)
EPROTONOSUPPORT (C++11)	不支持协议 (宏常量)
EPROTOTYPE (C++11)	协议类型与套接字不匹配 (宏常量)
ERANGE	结果过大 (宏常量)
EROFS (C++11)	只读文件系统 (宏常量)
ESPIPE (C++11)	无效的 seek (宏常量)
ESRCH (C++11)	没有这样的进程 (宏常量)
ETIME (C++11)	STREAM ioctl() 超时 (宏常量)
ETIMEDOUT (C++11)	连接超时 (宏常量)
ETXTBSY (C++11)	文本文件忙 (宏常量)
EWOULDBLOCK (C++11)	操作将被阻塞 (宏常量)
EXDEV (C++11)	跨设备链接 (宏常量)

所有值都必须唯一，但 EOPNOTSUPP 和 ENOTSUP 的值可能相同，EAGAIN 和 EWOULDBLOCK 的值也可能相同。

[编辑] 示例

运行此代码

#include <cerrno>
#include <cstring>
#include <iomanip>
#include <iostream>
 
#define SHOW(x) std::cout << std::setw(15) << #x << ": " << std::strerror(x) << '\n'
 
int main()
{
    std::cout << "Known error codes/messages:\n\n";
 
    SHOW( E2BIG );
    SHOW( EACCES );
    SHOW( EADDRINUSE );
    SHOW( EADDRNOTAVAIL );
    SHOW( EAFNOSUPPORT );
    SHOW( EAGAIN );
    SHOW( EALREADY );
    SHOW( EBADF );
    SHOW( EBADMSG );
    SHOW( EBUSY );
    SHOW( ECANCELED );
    SHOW( ECHILD );
    SHOW( ECONNABORTED );
    SHOW( ECONNREFUSED );
    SHOW( ECONNRESET );
    SHOW( EDEADLK );
    SHOW( EDESTADDRREQ );
    SHOW( EDOM );
    SHOW( EEXIST );
    SHOW( EFAULT );
    SHOW( EFBIG );
    SHOW( EHOSTUNREACH );
    SHOW( EIDRM );
    SHOW( EILSEQ );
    SHOW( EINPROGRESS );
    SHOW( EINTR );
    SHOW( EINVAL );
    SHOW( EIO );
    SHOW( EISCONN );
    SHOW( EISDIR );
    SHOW( ELOOP );
    SHOW( EMFILE );
    SHOW( EMLINK );
    SHOW( EMSGSIZE );
    SHOW( ENAMETOOLONG );
    SHOW( ENETDOWN );
    SHOW( ENETRESET );
    SHOW( ENETUNREACH );
    SHOW( ENFILE );
    SHOW( ENOBUFS );
    SHOW( ENODATA );
    SHOW( ENODEV );
    SHOW( ENOENT );
    SHOW( ENOEXEC );
    SHOW( ENOLCK );
    SHOW( ENOLINK );
    SHOW( ENOMEM );
    SHOW( ENOMSG );
    SHOW( ENOPROTOOPT );
    SHOW( ENOSPC );
    SHOW( ENOSR );
    SHOW( ENOSTR );
    SHOW( ENOSYS );
    SHOW( ENOTCONN );
    SHOW( ENOTDIR );
    SHOW( ENOTEMPTY );
    SHOW( ENOTRECOVERABLE );
    SHOW( ENOTSOCK );
    SHOW( ENOTSUP );
    SHOW( ENOTTY );
    SHOW( ENXIO );
    SHOW( EOPNOTSUPP );
    SHOW( EOVERFLOW );
    SHOW( EOWNERDEAD );
    SHOW( EPERM );
    SHOW( EPIPE );
    SHOW( EPROTO );
    SHOW( EPROTONOSUPPORT );
    SHOW( EPROTOTYPE );
    SHOW( ERANGE );
    SHOW( EROFS );
    SHOW( ESPIPE );
    SHOW( ESRCH );
    SHOW( ETIME );
    SHOW( ETIMEDOUT );
    SHOW( ETXTBSY );
    SHOW( EWOULDBLOCK );
    SHOW( EXDEV );
}

可能的输出

Known error codes/messages:
 
          E2BIG: Argument list too long
         EACCES: Permission denied
     EADDRINUSE: Address already in use
  EADDRNOTAVAIL: Cannot assign requested address
   EAFNOSUPPORT: Address family not supported by protocol
         EAGAIN: Resource temporarily unavailable
       EALREADY: Operation already in progress
          EBADF: Bad file descriptor
        EBADMSG: Bad message
          EBUSY: Device or resource busy
      ECANCELED: Operation canceled
         ECHILD: No child processes
   ECONNABORTED: Software caused connection abort
   ECONNREFUSED: Connection refused
     ECONNRESET: Connection reset by peer
        EDEADLK: Resource deadlock avoided
   EDESTADDRREQ: Destination address required
           EDOM: Numerical argument out of domain
         EEXIST: File exists
         EFAULT: Bad address
          EFBIG: File too large
   EHOSTUNREACH: No route to host
          EIDRM: Identifier removed
         EILSEQ: Invalid or incomplete multibyte or wide character
    EINPROGRESS: Operation now in progress
          EINTR: Interrupted system call
         EINVAL: Invalid argument
            EIO: Input/output error
        EISCONN: Transport endpoint is already connected
         EISDIR: Is a directory
          ELOOP: Too many levels of symbolic links
         EMFILE: Too many open files
         EMLINK: Too many links
       EMSGSIZE: Message too long
   ENAMETOOLONG: File name too long
       ENETDOWN: Network is down
      ENETRESET: Network dropped connection on reset
    ENETUNREACH: Network is unreachable
         ENFILE: Too many open files in system
        ENOBUFS: No buffer space available
        ENODATA: No data available
         ENODEV: No such device
         ENOENT: No such file or directory
        ENOEXEC: Exec format error
         ENOLCK: No locks available
        ENOLINK: Link has been severed
         ENOMEM: Cannot allocate memory
         ENOMSG: No message of desired type
    ENOPROTOOPT: Protocol not available
         ENOSPC: No space left on device
          ENOSR: Out of streams resources
         ENOSTR: Device not a stream
         ENOSYS: Function not implemented
       ENOTCONN: Transport endpoint is not connected
        ENOTDIR: Not a directory
      ENOTEMPTY: Directory not empty
ENOTRECOVERABLE: State not recoverable
       ENOTSOCK: Socket operation on non-socket
        ENOTSUP: Operation not supported
         ENOTTY: Inappropriate ioctl for device
          ENXIO: No such device or address
     EOPNOTSUPP: Operation not supported
      EOVERFLOW: Value too large for defined data type
     EOWNERDEAD: Owner died
          EPERM: Operation not permitted
          EPIPE: Broken pipe
         EPROTO: Protocol error
EPROTONOSUPPORT: Protocol not supported
     EPROTOTYPE: Protocol wrong type for socket
         ERANGE: Numerical result out of range
          EROFS: Read-only file system
         ESPIPE: Illegal seek
          ESRCH: No such process
          ETIME: Timer expired
      ETIMEDOUT: Connection timed out
        ETXTBSY: Text file busy
    EWOULDBLOCK: Resource temporarily unavailable
          EXDEV: Invalid cross-device link

[编辑] 另请参阅

errc (C++11)	the std::error_condition 列出所有标准 `<cerrno>` 宏常量的枚举 (类) [编辑]
errno	扩展为与 POSIX 兼容的线程本地错误号变量的宏 (宏变量)[编辑]
perror	将与当前错误对应的字符字符串显示到 stderr (函数) [编辑]
strerror	返回给定错误码的文本版本 (函数) [编辑]
C 文档 for 错误号

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