fopen problem How does it work?

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André Luiz Regis Monteiro 2014-2-10

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https://ww2.mathworks.cn/matlabcentral/answers/115583-fopen-problem-how-does-it-work

评论： Image Analyst 2014-2-11

I have a file VarName3.txt like this:

[2.281000003
593500003
749750003
062250003
062250003...

and negative values too. It is 1x1000.

The code I am using is:

fid=fopen('VarName3.txt','r');
atensao=fread(fid,'float');
fclose(fid);

When I type in Comand Window to check atensao, the answer is:

Why it doesn't work? What am I doing wrong? Could someone teach me? Thanks a lot.

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Answer 1

dpb 2014-2-10

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https://ww2.mathworks.cn/matlabcentral/answers/115583-fopen-problem-how-does-it-work#answer_123900

在 MATLAB Online 中打开

fid=fopen('VarName3.txt','r'); 
atensao=fread(fid,'float'); 
fclose(fid);

Surprising got anything that reasonable. If the input file is actually an ASCII text file, then use fscanf instead of fread. fread is for stream unformatted data, not formatted.

fid=fopen('VarName3.txt','r'); 
atensao=fscanf(fid,'%f'); 
fclose(fid);

Or use one of the higher-level routines--while deprecated by TMW, textread is awfully handy for such simple cases as it wraps the fopen/fclose in the call and returns an array rather than a cell for the much fancier textscan

atensao=textread('VarName3.txt');

even allowing to dispense with the format string for simple numeric data such as your case. See

doc textread
doc textscan
doc fscanf

for more details

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André Luiz Regis Monteiro 2014-2-11

编辑：André Luiz Regis Monteiro 2014-2-11

Thank you "dpb". I really appreciated. But when I check "atensao" it shows me number like: 2.2810 instead of 2.281000003 (from original file VarName3.txt). Do you know how can I fix it? Thank you again.