open打开已有文件出错,segmentation fault, invalid memory reference

pasuka

Fortran规范写得很明白，传送门https://docs.oracle.com/cd/E1995 ... j4m0vnaf/index.html

STATUS=sta
The STATUS=sta clause is optional. sta is a character expression. Possible values are: 'OLD', 'NEW', 'UNKNOWN', or 'SCRATCH'.
'OLD'-- The file already exists (nonexistence is an error). For example: STATUS='OLD'.
'NEW' -- The file doesn't exist (existence is an error). If 'FILE=name' is not specified, then a file named 'fort.n' is opened, where n is the specified logical unit.
'UNKNOWN' -- Existence is unknown. This is the default.
'SCRATCH' -- For a file opened with STATUS='SCRATCH', a temporary file with a name of the form tmp.FAAAxnnnnn is opened. Any other STATUS specifier without an associated file name results in opening a file named 'fort.n', where n is the specified logical unit number. By default, a scratch file is deleted when closed or during normal termination. If the program aborts, then the file may not be deleted. To prevent deletion, CLOSE with STATUS='KEEP'.
The FORTRAN 77 Standard prohibits opening a named file as scratch: if OPEN has a FILE=name option, then it cannot have a STATUS='SCRATCH' option. This FORTRAN extends the standard by allowing opening named files as scratch. @ Such files are normally deleted when closed or at normal termination.
TMPDIR: FORTRAN programs normally put scratch files in the current working directory. If the TMPDIR environment variable is set to a writable directory, then the program puts scratch files there. @

Stack Overflow上面的类似问题以及解决建议
https://stackoverflow.com/questi ... and-the-append-data

pasuka

mao 发表于 2018-2-5 13:35
谢谢。
看过OPEN的说明，我的代码应该是对的吧，现在的问题是：Status=‘OLD’时候， 文件存在会出错。 ...

文档不是说了吗？'OLD'-- The file already exists (nonexistence is an error). 文件若是不存在则报错
程序代码没有问题，不能推导出程序要打开的文件及其路径也没问题啊？
再说，Stack Overflow上面的帖子已经给出参考代码，为啥不试着跑跑呢？
师傅领进门，修行在自身。

pasuka

mao 发表于 2018-2-5 13:54
谢谢回复，我试过如下代码。
文件不存在时候，新建和写入都正常。再执行一次（此时文件存在，刚新建的） ...

MSYS2 + Gfortran 7.3.0 测试正常

[Fortran] 纯文本查看 复制代码

program main
implicit none
logical:: exist
integer:: flag
character(len=8):: fn="demo.txt"
  
inquire(file=fn, exist=exist)
if (exist) then
    write(*,*)"File already exists."
    open(newunit=flag, file=fn, status="old")
    write(flag, *)"Rewrite file."
    close(flag)
else
    write(*,*)"File does not exist"
    open(newunit=flag, file=fn, status="new")
    write(flag, *)"Create file."
    close(flag)
end if
end program

pasuka

mao 发表于 2018-2-5 15:16
谢谢。

我也运行了你的代码，一样的： 第一执行次文件不存在，新建写入正常，第二次执行文件存在，segmen ...

gfortran版本呢？CB自带是4.9系列吧？即使5.0版也有反馈出错的
https://sourceforge.net/p/tdm-gcc/bugs/270/

pasuka

mao 发表于 2018-2-5 15:54
谢谢。

现在看起来极有可能是这个编译器版本问题。

命令行下面执行gcc -v或者gfortran -v就能查看版本号

pasuka

mao 发表于 2018-2-6 12:54
谢谢 VVT 和 pasuka 的回答。目前问题已经解决了： 是gFortran编译器版本的问题，如pasuka所说。

我从MinG ...

不客气
我不用CB这类IDE做Fortran程序开发，写Makefile也挺好啊
安装新版gcc可以用MSYS2

pasuka

mao 发表于 2018-2-7 11:39
前天刚装了个MSYS2， 刚接触还不太会用，学习中，有什么好的适合入门的资料么？thanks ...

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网上MSYS2的配置教程很多
使用的话，首先得了解Linux基本命令，譬如：
http://linuxtools-rst.readthedocs.io/zh_CN/latest/index.html
http://wiki.ubuntu.org.cn/%E7%BC%96%E7%A8%8B%E8%AF%AD%E8%A8%80