How do I put spaces before a line in a txt file using strcat and fprintf?

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Ali Almakhmari
Ali Almakhmari 2023-4-16
编辑： Image Analyst 2023-4-16
How do I put spaces before a line in a txt file using strcat and fprintf?
When I go in MATLAB and try to print ' 1,2,3' in the file opened in fid_wrt as shown below. I will find that the file has '1,2,3', without the spaces.
B{1} = '%.4f,%.4f,%.4f';
fprintf(fid_wrt,strcat(' \n',B{1},','),1:1:3);
I tried adding the spaces before \n...after it...nothing. I just can't get those spaces in the fid_wrt file. I just want those spaces before the numbers man. Whats weird is that fprintf (without writing in the file) does show those spaces in the command window!!

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采纳的回答

Stephen23
Stephen23 2023-4-16
STRCAT removes whitespace characters. The easy and robust approach is separate FPRINTF calls:
fprintf(fid_wrt,' \n')
fprintf(fid_wrt,B{1},1:1:3)
fprintf(fid_wrt,',')

更多回答（1 个）

Image Analyst
Image Analyst 2023-4-16
strcat does an automatic trim of spaces. Just use fprintf alone. No need for B or strcat.
% Have a line with spaces on it before the line with numbers on it.
fprintf(fid_wrt,' \n%.4f, %.4f, %.4f\n', 1 : 3);
  2 个评论
Ali Almakhmari
Ali Almakhmari 2023-4-16
The thing is, B{1} changes in the code...its not something that is a constant. So I need strcat to concatenate B{1} in the fprintf.
Image Analyst
Image Analyst 2023-4-16
编辑：Image Analyst 2023-4-16
You could put B in as a string
% Define a format specifier string using B.
B{1} = ' \n%.4f,%.4f,%.4f\n';
formatSpecifier = B{1};
% Have a line with spaces on it before the line with numbers on it.
fprintf(fid_wrt, formatSpecifier, 1 : 3);

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