How to have a variable format spec print length when using fprintf?

Question

AdamG2013468 2019-8-15

0
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https://ww2.mathworks.cn/matlabcentral/answers/476288-how-to-have-a-variable-format-spec-print-length-when-using-fprintf

回答： Jess Lovering 2019-8-15

I am trying to print column header information to a .txt file using fprintf. I am importing the column header information from another file. The problem is that the imported column header information can be any character length, as defined by the user (e.g. could be 1 character long, could be 20). I would like to use the maximum header length to define how much space will be needed when printing the column headers/labels. The code in question is summarized below:

for i = 1:length(headerinformation)
    fprintf(fid,'%10s',headerinformation{i})
end

The default amount of space I am using is 10 (i.e. %10s), but this doesn't work well when the headers are > 10. At first i tried using the maximum header lenth variable to define the maximum header length, but this didn't work properly when using the fprintf format spec. I tried something similar to the following:

MaxHeaderLength = max(cell2mat(columnheaderlength));
for i = 1:length(headerinformation)
    fprintf(fid,'%(%i)s',headerinformation{i}, MaxHeaderLength) %parenthesis around %i added for explanation only, i know this wouldn't actually work
end

Any guidance would be appreciated.