Extracting a number from an input (text file)?

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Amin
Amin 2011-5-27
in the middle of my program, I need to read a Number from a file (text or DAT). This is a part of the file
##$SUBNAM9= <"">
##$SW= 2776.7173944802
##$SWIBOX= (0..15)
0 0 2 0 0 0 0 0 0 0 0 0 0 0 0 0
##$SW_h= 833333.333333333
##$SWfinal= 0
##$TD= 16384
##$TD0= 1
##$TE= 300
##$TE2= 300
I want Matlab to first read this file, then search for the number in front of "##$TD= ", which is 16384 in this example. Then
TD = 16384;
Thanks in advance

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采纳的回答

Walter Roberson
Walter Roberson 2011-5-27
T = regexp(TheString, '^##\$TD=\s*(.*) \s*$', 'tokens');
Then T{1} will be the string of the number. str2double(T{1}) if you want the numeric value.
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Walter Roberson
Walter Roberson 2011-5-29
Darn default behaviours...
T = regexp(TheString, '(?-s)(?m)^##\$TD=\s*(\S+)\s*$', 'tokens');
The exact pattern to use depends on whether you have lines that have embedded spaces and on whether you need to trim the trailing spaces from such lines.

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更多回答（1 个）

Laura Proctor
Laura Proctor 2011-5-27
I'll put my answer here since it's a little different, but Walter's response is definitely a lot more elegant.
fid = fopen('data.txt');
dataText = fgetl(fid);
while ~feof(fid)
if strfind(dataText,'##$TD')
ldata = textscan(dataText,'##$%s %f');
TD = ldata{2};
break
end
dataText = fgetl(fid);
end
fclose(fid);
  2 个评论
Walter Roberson
Walter Roberson 2011-5-27
strfind() used in that way would find ##$TD anywhere in the string, but the following textscan() would only match if the line started with $$# . The difference could potentially be a problem -- e.g., if the user had happened to use a comment that included ##$TD as part of it.
strncmp(dataText,'##$TD',5) would be more robust than strfind() in this matter.
Amin
Amin 2011-5-28
This solution is much more understandable for basic people like me. But the 'one line' code from Walter Roberson is so elegant.
I use strncmp(dataText,'##$TD',5) instead of strfind() for this. Thank you Laura Proctor.

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