FREAD() help

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!

Answer 1

[Jan]

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.

Answer 2

[Sean de Wolski]

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.

[Edward]

I've tried changing it to use fread(fid,4,'double'); but still get the same random numbers