Why do I receive the error "Inavlid file identifier" when using fopen?

Question

Leah 2012-7-9

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/43164-why-do-i-receive-the-error-inavlid-file-identifier-when-using-fopen

评论： Eldhose Poulose 2020-5-9

function spec = abc(filelist);
  filelist='filelist23.txt';
  fl = importdata(filelist);
    nFile = size(fl,1);
    %fid = fopen(file);
    Nbins = 1024;
    spec = zeros(nFile, Nbins);
    for iFile = 1:nFile
      fid=fopen(fl{iFile})
      % Read the 18 header text lines (but not the entire line, and discard)
      for i=1:18 hdr=textscan(fid,'%s %*[^\n]',1); end
      x=textscan(fid,'%d%d','delimiter',',,');
      x = x{:,1};
      x = reshape(x,2,Nbins);
      spec(iFile,:) = x(2,:);
      fclose(fid);
    end
  end

I get an error at fopen--I get the number -1 which is inccorect and i have no idea how to fix it. The error message is:

??? Error using ==> textscan
Invalid file identifier.  Use fopen to generate a valid file identifier.
Error in ==> rdUCS30MCA at 23
    for i=1:18 hdr=textscan(fid,'%s %*[^\n]',1);

2 个评论
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Jan 2012-7-16

Not nice, Leah. You found out that you cannot delete a thread after somebody has answered. Then you decided to overwrite the text by nonsense. This is a misuse of the idea of a public forum.

Randy Souza 2012-10-18

I restored the original question based on Lucas' assertion that this question might help others.

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Answer 1

Jan 2012-7-10

3
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/43164-why-do-i-receive-the-error-inavlid-file-identifier-when-using-fopen#answer_53074

在 MATLAB Online 中打开

Every fopen() should be accompanied by a check of the results:

fid = fopen(fl{iFile});
if fid == -1
  error('Author:Function:OpenFile', 'Cannot open file: %s', fl{iFile});
end

File access is prone to problems. A stable program catchs them and the time wasted by debugging can be reduced, if an exhaustive error message is displayed.