How to open a binary file that returns -1 when using fopen?

I am trying to open a file that someone else recorded. The file is supposedly binary. The extension is meaningless (it refers to the content of the file...). I tried using fopen and the file identifier is -1 (so can't read it in). If I 'manually' open the file it does not show as binary but as many symbols. How can I approach this?

Thank you

Answer 1

[Walter Roberson]

Use

filename = 'NameOfBinaryFile';

[fid, msg] = fopen(filename, 'r');
if fid < 0
   error('Could not open file "%s" because: "%s"', filename, msg);
end

For example it might be in use by another program, or you might not have permission to read it.

[Cristina]

I am not trying to make my program available to others. I am trying to analyse the data that is stored in the binary file. The binary data seems to be converted into characters if I open the file with an editor, and the file can't be open at all in MATLAB. I am trying to access the binary data.

[Walter Roberson]

Currently you do not know why the fopen fails. The above code will tell you why. It has nothing to do with making your program available to others: it has to do with debugging a problem with your program or configuration.

Answer 2

[Image Analyst]

Check the file attributes. If it's marked at readonly and you're trying to open it for writing, it might return -1. Make sure the readonly checkbox is not checked.