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FREAD() help

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Edward
Edward am 4 Apr. 2012
Hi so im trying to use fread in a very simple program. Ive used the following to write 4 numbers into a .txt file:
fid=fopen('data.txt','wt');
fprintf(fid,'%0.0f %0.0f %0.0f %0.0f', 2, 4, 6, 8);
fclose(fid);
Now i want to read the data back in by reopening the file and reading into an array:
fid=fopen('data.txt');
numbers=fread(fid);
now if i output 'numbers' i get some completely random numbers:
[ 50 32 52 32 54 32 56]
What am i doing wrong? I should be getting [2 4 6 8] back?
Also if anyone knows why im getting an output 'ans=0' that would be useful too.
Thanks!

Akzeptierte Antwort

Jan
Jan am 4 Apr. 2012
fprintf writes the data as ASCII strings, so you get the string "2 4 6 8" in the file. The binary representation of this string is:
Str = '2 4 6 8';
double(Str)
>> 50 32 52 32 54 32 56
E.g. char(32) is the space character.
Strings written by fprintf are read by fscanf:
fid = fopen('data.txt');
numbers = fscanf(fid, '%f %f %f %f);
fread is thought for reading data written by fwrite.
See also the help and doc for these 4 commands.

Weitere Antworten (1)

Sean de Wolski
Sean de Wolski am 4 Apr. 2012
You have to specify the precision of the numbers you're reading (i.e. double).
You could also look at dlmread and dlmwrite if the whole text file will be numbers.
  1 Kommentar
Edward
Edward am 4 Apr. 2012
I've tried changing it to use fread(fid,4,'double'); but still get the same random numbers

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