Reading a binary data file

Hello,

I am trying to import and read a binary data file of the following format in MATLAB. I need to read in all the data, however at this point im just trying to read in the first 4 char, but i keep getting a blank array. Nothing seems to be working and I have been stuck for days.

Thanks in advance for your help!

fid = fopen('file.dat','r');

if fid <0
    error('error opening file %s\n file.dat')
end
Program_label = fread(fid,[1 4],*char)


fclose(fid);

m = memmapfile('GSS1_t023_is_phcorr_ideal.dat');
m.Format

Answer 1

[Jan]

fid = fopen('file.dat','r');
if fid <0
    error('error opening file %s\n file.dat')
end

Program_label   = fread(fid, [1 4], '*char');   % With quotes
Program_version = fread(fid, 1, 'single');
Type_label      = fread(fid, [1 4], '*char');
nCols           = fread(fid, 1, 'uint32');
nRows           = fread(fid, 1, 'uint32');
...
fclose(fid);

[KatherineS]

Thank you for your answer, however the output for the values just shows as [] rather than the actual data, is there a way to fix this?

[Jan]

Please explain exactly, what you are doing. How do you obatin the "[]"? "The output for the values shows..." is not clear enough to understand this. Program_label is read as char vector, such that it is unlikely, that the empty matrix [] is shown anywhere. Therefore I assume, that your method to display the contents of the variables is flawed, or that the file really contains '[] ' as first 4 characters.

[KatherineS]

Running the code you provided on the file, I obtain what is shown in the image in my workspace. the first characters in the file should be imageLayerStack (abcdef1 v 1.14)

[Walter Roberson]

Please show us

double(Program_label)

I suspect that it contains unprintable characters, such as binary 0.

the first characters in the file should be imageLayerStack (abcdef1 v 1.14) 

That disagrees with the layout you provided, which says that there should be 4 characters followed by a single precision float

[Jan]

Show us:

fid = fopen('file.dat','r');
if fid <0
    error('error opening file %s\n file.dat')
end
data = fread(fid, [1 16], '*uint8')
fclose(fid)

[KatherineS]

Hello,

The data variable shows as (in image) and double(Program_label) shows as []

Thank you all very much for your help in this.

[Walter Roberson]

The file is empty.

[Walter Roberson]

dinfo = dir('file.dat')

and look at the bytes information. I think it will show 0