strerror 函数

参考链接： C++ strerror()

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 strerror编辑 

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  编辑吧！

     通过标准错误的标号，获得错误的描述字符串 ，将单纯的错误标号转为字符串描述，方便用户查找错误。

     外文名 

      strerror

     语    言 

      C语言

     参    数 

      错误标号（即error）

     返回值 

      描述字符串（char *）

  目录 

    1函数名 

    2函数作用 

    3头文件 

    4函数原型 

    5举例 

  1函数名编辑 

   strerror, _strerror, _wcserror, __wcserror

  2函数作用编辑 

   Get a system error message (strerror, _wcserror) or prints a user-supplied error message (_strerror, __wcserror).

   获取系统

   错误信息或打印用户

   程序错误信息。

  3头文件编辑 

   #include <string.h>

  4函数原型编辑 

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           char

           *

           strerror

           (interrnum);

           char

           *_strerror(constchar*strErrMsg);

           wchar_t

           *_wcserror(interrnum);

           wchar_t

           *__wcserror(constwchar_t*strErrMsg)

   参数：

   errnum：错误标号，通常用errno(标准错误号，定义在errno.h中)

   Error number.

   strErrMsg

   User-supplied message.

   返回：

   指向

   错误信息的

   指针（即：错误的描述字符串）。

  5举例编辑 

   例一：

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           #include<stdio.h>

           #include<string.h>

           #include<errno.h>

           #include<stdlib.h>

           intmain(

           void

           )

           {

           FILE

           *fp;

           externinterrno;

           char

           *message;

           if

           (NULL==(fp=

           fopen

           (

           "/dev/dsp"

           ,

           "r+"

           )))

           {

           printf

           (

           "errno=%d\n"

           ,

           errno

           );

           message=

           strerror

           (

           errno

           );

           printf

           (

           "Mesg:%s\n"

           ,message);

           }

           exit

           (0);

           }

   输出：

   error=2

   Mesg:No such file or direcory

   例二：

   // crt_perror.c

   // compile with: /W1

   /* This program attempts to open a file named

   * NOSUCHF.ILE. Because this file probably doesn't exist,

   * an error message is displayed. The same message is

   * created using perror, strerror, and _strerror.

   */

   #include <fcntl.h>

   #include <sys/types.h>

   #include <sys/stat.h>

   #include <io.h>

   #include <stdlib.h>

   #include <stdio.h>

   #include <string.h>

   #include <share.h>

   int main( void )

   {

   int fh;

   if( _sopen_s( &fh, "NOSUCHF.ILE", _O_RDONLY, _SH_DENYNO, 0 ) != 0 )

   {

   /* Three ways to create error message: */

   perror( "perror says open failed" );

   printf( "strerror says open failed: %s\n",

   strerror( errno ) ); // C4996

   printf( _strerror( "_strerror says open failed" ) ); // C4996

   // Note: strerror and _strerror are deprecated; consider

   // using strerror_s and _strerror_s instead.

   }

   else

   {

   printf( "open succeeded on input file\n" );

   _close( fh );

   }

   }

   输出：

   perror says open failed: No such file or directory

   strerror says open failed: No such file or directory

   _strerror says open failed: No such file or directory

   转自　：　http://baike.baidu.com/link?url=pllZsYxUR2EJ26CRuWn_F8x7cUimLjEi6g_tPsEnENMv3L4zzXhwqtQ1u7ry8IrHbCh29BbgJTVACTPfawZ1J_

     linux下错误的捕获：errno和strerror的使用 

      经常在调用linux 系统api 的时候会出现一些错误，比方说使用open() write() creat()之类的函数有些时候会返回-1，也就是调用失败，这个时候往往需要知道失败的原因。这个时候使用errno这个全局变量就相当有用了。

          在程序代码中包含 #include <errno.h>,然后每次程序调用失败的时候，系统会自动用用错误代码填充errno这个全局变量，这样你只需要读errno这个全局变量就可以获得失败原因了。

          例如：

      #include <stdio.h>

      #include <string.h>

      #include <errno.h>

      int main(void)

      {

      int fd;

      extern int errno;

      if((fd = open("/dev/dsp",O_WRONLY)) < 0)

      {

         printf("errno=%d\n",errno);

      }

      exit(0);

      }

      如果dsp设备忙的话errno值将是16。

      errno.h中定义的错误代码值如下：

      查 看错误代码errno是调试程序的一个重要方法。当linuc C api函数发生异常时,一般会将errno变量(需include errno.h)赋一个整数值,不同的值表示不同的含义,可以通过查看该值推测出错的原因。在实际编程中用这一招解决了不少原本看来莫名其妙的问题。比较 麻烦的是每次都要去linux源代码里面查找错误代码的含义，现在把它贴出来，以后需要查时就来这里看了。

      以下来自linux 2.4.20-18的内核代码中的/usr/include/asm/errno.h

      #ifndef _I386_ERRNO_H

      #define _I386_ERRNO_H

      #define EPERM 1 /* Operation not permitted */

      #define ENOENT 2 /* No such file or directory */

      #define ESRCH 3 /* No such process */

      #define EINTR 4 /* Interrupted system call */

      #define EIO 5 /* I/O error */

      #define ENXIO 6 /* No such device or address */

      #define E2BIG 7 /* Arg list too long */

      #define ENOEXEC 8 /* Exec format error */

      #define EBADF 9 /* Bad file number */

      #define ECHILD 10 /* No child processes */

      #define EAGAIN 11 /* Try again */

      #define ENOMEM 12 /* Out of memory */

      #define EACCES 13 /* Permission denied */

      #define EFAULT 14 /* Bad address */

      #define ENOTBLK 15 /* Block device required */

      #define EBUSY 16 /* Device or resource busy */

      #define EEXIST 17 /* File exists */

      #define EXDEV 18 /* Cross-device link */

      #define ENODEV 19 /* No such device */

      #define ENOTDIR 20 /* Not a directory */

      #define EISDIR 21 /* Is a directory */

      #define EINVAL 22 /* Invalid argument */

      #define ENFILE 23 /* File table overflow */

      #define EMFILE 24 /* Too many open files */

      #define ENOTTY 25 /* Not a typewriter */

      #define ETXTBSY 26 /* Text file busy */

      #define EFBIG 27 /* File too large */

      #define ENOSPC 28 /* No space left on device */

      #define ESPIPE 29 /* Illegal seek */

      #define EROFS 30 /* Read-only file system */

      #define EMLINK 31 /* Too many links */

      #define EPIPE 32 /* Broken pipe */

      #define EDOM 33 /* Math argument out of domain of func */

      #define ERANGE 34 /* Math result not representable */

      #define EDEADLK 35 /* Resource deadlock would occur */

      #define ENAMETOOLONG 36 /* File name too long */

      #define ENOLCK 37 /* No record locks available */

      #define ENOSYS 38 /* Function not implemented */

      #define ENOTEMPTY 39 /* Directory not empty */

      #define ELOOP 40 /* Too many symbolic links encountered */

      #define EWOULDBLOCK EAGAIN /* Operation would block */

      #define ENOMSG 42 /* No message of desired type */

      #define EIDRM 43 /* Identifier removed */

      #define ECHRNG 44 /* Channel number out of range */

      #define EL2NSYNC 45 /* Level 2 not synchronized */

      #define EL3HLT 46 /* Level 3 halted */

      #define EL3RST 47 /* Level 3 reset */

      #define ELNRNG 48 /* Link number out of range */

      #define EUNATCH 49 /* Protocol driver not attached */

      #define ENOCSI 50 /* No CSI structure available */

      #define EL2HLT 51 /* Level 2 halted */

      #define EBADE 52 /* Invalid exchange */

      #define EBADR 53 /* Invalid request descriptor */

      #define EXFULL 54 /* Exchange full */

      #define ENOANO 55 /* No anode */

      #define EBADRQC 56 /* Invalid request code */

      #define EBADSLT 57 /* Invalid slot */

      #define EDEADLOCK EDEADLK

      #define EBFONT 59 /* Bad font file format */

      #define ENOSTR 60 /* Device not a stream */

      #define ENODATA 61 /* No data available */

      #define ETIME 62 /* Timer expired */

      #define ENOSR 63 /* Out of streams resources */

      #define ENONET 64 /* Machine is not on the network */

      #define ENOPKG 65 /* Package not installed */

      #define EREMOTE 66 /* Object is remote */

      #define ENOLINK 67 /* Link has been severed */

      #define EADV 68 /* Advertise error */

      #define ESRMNT 69 /* Srmount error */

      #define ECOMM 70 /* Communication error on send */

      #define EPROTO 71 /* Protocol error */

      #define EMULTIHOP 72 /* Multihop attempted */

      #define EDOTDOT 73 /* RFS specific error */

      #define EBADMSG 74 /* Not a data message */

      #define EOVERFLOW 75 /* Value too large for defined data type */

      #define ENOTUNIQ 76 /* Name not unique on network */

      #define EBADFD 77 /* File descriptor in bad state */

      #define EREMCHG 78 /* Remote address changed */

      #define ELIBACC 79 /* Can not access a needed shared library */

      #define ELIBBAD 80 /* Accessing a corrupted shared library */

      #define ELIBSCN 81 /* .lib section in a.out corrupted */

      #define ELIBMAX 82 /* Attempting to link in too many shared libraries */

      #define ELIBEXEC 83 /* Cannot exec a shared library directly */

      #define EILSEQ 84 /* Illegal byte sequence */

      #define ERESTART 85 /* Interrupted system call should be restarted */

      #define ESTRPIPE 86 /* Streams pipe error */

      #define EUSERS 87 /* Too many users */

      #define ENOTSOCK 88 /* Socket operation on non-socket */

      #define EDESTADDRREQ 89 /* Destination address required */

      #define EMSGSIZE 90 /* Message too long */

      #define EPROTOTYPE 91 /* Protocol wrong type for socket */

      #define ENOPROTOOPT 92 /* Protocol not available */

      #define EPROTONOSUPPORT 93 /* Protocol not supported */

      #define ESOCKTNOSUPPORT 94 /* Socket type not supported */

      #define EOPNOTSUPP 95 /* Operation not supported on transport endpoint */

      #define EPFNOSUPPORT 96 /* Protocol family not supported */

      #define EAFNOSUPPORT 97 /* Address family not supported by protocol */

      #define EADDRINUSE 98 /* Address already in use */

      #define EADDRNOTAVAIL 99 /* Cannot assign requested address */

      #define ENETDOWN 100 /* Network is down */

      #define ENETUNREACH 101 /* Network is unreachable */

      #define ENETRESET 102 /* Network dropped connection because of reset */

      #define ECONNABORTED 103 /* Software caused connection abort */

      #define ECONNRESET 104 /* Connection reset by peer */

      #define ENOBUFS 105 /* No buffer space available */

      #define EISCONN 106 /* Transport endpoint is already connected */

      #define ENOTCONN 107 /* Transport endpoint is not connected */

      #define ESHUTDOWN 108 /* Cannot send after transport endpoint shutdown */

      #define ETOOMANYREFS 109 /* Too many references: cannot splice */

      #define ETIMEDOUT 110 /* Connection timed out */

      #define ECONNREFUSED 111 /* Connection refused */

      #define EHOSTDOWN 112 /* Host is down */

      #define EHOSTUNREACH 113 /* No route to host */

      #define EALREADY 114 /* Operation already in progress */

      #define EINPROGRESS 115 /* Operation now in progress */

      #define ESTALE 116 /* Stale NFS file handle */

      #define EUCLEAN 117 /* Structure needs cleaning */

      #define ENOTNAM 118 /* Not a XENIX named type file */

      #define ENAVAIL 119 /* No XENIX semaphores available */

      #define EISNAM 120 /* Is a named type file */

      #define EREMOTEIO 121 /* Remote I/O error */

      #define EDQUOT 122 /* Quota exceeded */

      #define ENOMEDIUM 123 /* No medium found */

      #define EMEDIUMTYPE 124 /* Wrong medium type */

      #endif

      同时也可以使用strerror（）来自己翻译

      如：

      #include <stdio.h>

      #include <string.h>

      #include <errno.h>

      int main(void)

      {

      int fd;

      extern int errno;

      if((fd = open("/dev/dsp",O_WRONLY)) < 0)

      {

         printf("errno=%d\n",errno);

      char * mesg = strerror(errno);

         printf("Mesg:%s\n",mesg);

      }

      exit(0);

      }

      dsp设备忙的话将输出如下：

      errno=16

      Mesg:Device or resource busy

     转自　http://www.douban.com/note/165931644/

转载于:https://www.cnblogs.com/IceSword-syy/p/4261834.html