How to change the loop 'for' to 'while'?

Question

MIHYUN 2014-9-22

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https://ww2.mathworks.cn/matlabcentral/answers/155743-how-to-change-the-loop-for-to-while

编辑： Stephen23 2014-9-22

采纳的回答： Stephen23

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I have cord and files.

File names are {trj.hst.01.+00, trj.hst.02.+00, trj.hst.03.+00, ...}

And the cord is

 for c=1:34
    file = sprintf('trj.hst.%02d.+00',c);
    fid = fopen(file);
    tline = fgetl(fid);
...

c is 1 to 34. But the last number can be changed at any time .

So, I want to change loop 'for' to 'while'.

(There is also a file with a different name in the folder . like as {thm.hst.00.+00,thm.hst.01.+00..})

Please help me.

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Guillaume 2014-9-22

What do you mean can be changed at any time? Isn't it fixed once you call your program. If not, under what condition does it change?

As for the file with the different name, you actually haven't asked a question. What do you want to with it, open it at the same time as the trj file?

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Answer 1

Stephen23 2014-9-22

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编辑：Stephen23 2014-9-22

MATLAB doesn't handle changes to a for loop variable easily, so your idea to use a while loop is ingenious. However I would suggest that you use a for loop anyway, which is a much more standard way of parsing multiple files in a loop using MATLAB. You will find some examples of how to do this here:

http://matlab.wikia.com/wiki/FAQ#How_can_I_process_a_sequence_of_files.3F

http://stackoverflow.com/questions/15366374/how-can-i-load-100-files-with-similar-names-and-or-string-in-just-one-step-in-matlab

As you can see, the basic idea is dir to get a list of the files, and then read the files' data using the function of your choice, such as textscan, fgetl, fileread, etc.

If you really must use a while loop, then you could exist to check if the file really exists and to decide when the loop terminates (perhaps with a break). If you use exist, you will also need to use its second (optional) input.