读取直接访问文件时，GFortran I / O错误5002 [英] GFortran I/O error 5002 while reading a direct access file

问题描述

在Fortran中读取文件时遇到一些问题。正如你所看到的，我正在浏览一个读取特定长度的记录的文件。

会发生什么事情，当涉及某个记录时，我得到一个IOSTAT错误5002.现在我的问题是这个错误是什么意思：是文件结束还是没有记录或其他东西？我可以忽略它吗？

我使用MinGW GFortran 4.8.0。

以下是代码：

  PROGRAM test_read 
 
 INTEGER * 4 HCM_error 
 DOUBLE PRECISION N_Record（22）
 CHARACTER * 8 C_Record（22）
 
 EQUIVALENCE（N_Record，C_Record）
 
 OPEN（UNIT = 11，FILE ='C：/BORDER/D__HOL.000',STATUS= 'OLD'，ACCESS ='DIRECT'，RECL = 176，ACTION ='READ'，IOSTAT = IOS）
 
 HCM_error = 0 
 
 DO N_rec = 1,200 
 READ（11，REC = N_rec，IOSTAT = IOS）C_Record 
 
 WRITE（*，*）|，IOS，''，N_rec，''，N_record（21），' ，N_record（22）， | 
 
！到达文件结尾（或不存在的记录）？ （IOS .LT。0）.OR。（IOS .EQ。36））退出
 
 IF（IOS .NE。0）THEN 
！ 
 HCM_Error = 1049 
 EXIT 
 END IF 
 END DO 
 
 CLOSE（UNIT = 11）
 
 WRITE（*，*）HCM_error 
 END PROGRAM 
  

解决方案

由 iostat = 指定符返回的非零值在编译器中不可移植。如果你想确定一个特定的代码是什么意思，那么你有两个选择：

• 阅读编译器的文档（如果存在的话）


• 使用带有字符变量的 iomsg = 说明符

在这种情况下，当您尝试 iomsg = 时，您收到消息不存在记录编号。所以，问题解决了。

好吧，差不多。还有更多要说的。

您可能会感到惊讶，因为您正在直接访问记录，但在达到无记录状态时未先达到文件结束状态。您正在测试（IOS .LT。0），并发表评论！文件已到达。

当读取直接访问连接的文件时，不会出现文件结尾条件。

您可以如何检测记录不是有效的数字文件的结尾？并不多，便携式，但任何来自 iostat = 的正数表示错误情况。不过，你现在知道，这个特定的 5002 的含义是什么。

---

我还可以补充说，只有在没有成功的情况下， iomsg = 的字符变量才由传输语句定义。只有当你知道转移失败时才考虑它。

I have a little Problem reading a file in Fortran. As you can see I am lopping over a file reading certain records with a specific length.

What happens is, when it comes to a certain record I'm getting an IOSTAT Error 5002. Now my question is what does this error mean: is it end of file or there is no record left or something else? Can I ignore it?

I am using MinGW GFortran 4.8.0.

Here's the code:

PROGRAM test_read

INTEGER*4           HCM_error
DOUBLE PRECISION    N_Record(22)
CHARACTER*8         C_Record(22)

EQUIVALENCE         (N_Record,C_Record)

OPEN (UNIT=11, FILE='C:/BORDER/D__HOL.000',STATUS='OLD', ACCESS='DIRECT',RECL=176, ACTION='READ', IOSTAT=IOS)

HCM_error=0

DO N_rec = 1, 2000
    READ (11, REC=N_rec, IOSTAT=IOS) C_Record

    WRITE(*,*) "|",IOS,' ',N_rec,' ',N_record(21),' ',N_record(22),"|"

    !End of file reached (or non existing record) ?
    IF ((IOS .LT. 0) .OR. (IOS .EQ. 36)) EXIT

    IF (IOS .NE. 0) THEN
        !Error in (border-) line data
        HCM_Error = 1049
        EXIT
    END IF
END DO

CLOSE(UNIT=11)

WRITE (*,*) HCM_error 
END PROGRAM

解决方案

The non-zero values returned by an iostat= specifier are not portable across compilers. If you wish to determine what a particular code means then you have two options:

• read the compiler's documentation (if it exists)
• use the iomsg= specifier with a character variable

In this case, when you tried iomsg= you got the message "Non-existing record number". So, problem solved.

Well, almost. There's more to say.

You may be surprised that you are going through records in turn in direct access, but are reaching a "no record" state without first reaching an "end of file" state. You are testing (IOS .LT. 0) with a comment "!End of file reached".

When reading a file connected for direct access, the end of file condition doesn't arise.

What can you do to detect that the record isn't a valid number, beyond the end of the file? Not much, portably, but any positive number from iostat= indicates an error condition. You know now, though, what this particular 5002 means.

---

I should probably also add that the character variable for iomsg= is defined by the transfer statement only if there isn't success. Consider it only if you know the transfer failed.

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