[Octave-bug-tracker] [bug #63931] Binary fwrite writes incorrect data to file

[anonymous]

URL:
  <https://savannah.gnu.org/bugs/?63931>

                 Summary: Binary fwrite writes incorrect data to file
                   Group: GNU Octave
               Submitter: None
               Submitted: Wed 15 Mar 2023 06:33:45 PM UTC
                Category: Octave Function
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
                 Release: 8.1.0
         Discussion Lock: Any
        Operating System: Microsoft Windows
           Fixed Release: None
         Planned Release: None


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Follow-up Comments:


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Date: Wed 15 Mar 2023 06:33:45 PM UTC By: Anonymous
If you open a file for binary write and use fwrite write a vector of uint8
values to the file, some of them get changed.  Specifically, writing hex A7
ends up in the file as hex 3F...

Here's a short script that generates incorrect results...


val = hex2dec('a7');
a = ones(2400,1)*val;
f = fopen('a.a','wb');
fwrite(f,a,'uint8');
fclose(f);

f = fopen('a.a','rb');
b = fread(f,2400,'uint8');
fclose(f);

a(1)
b(1)









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