MATLAB: Invalid file identifier. Use fopen to generate a valid file identifier.

file identifier

Hello,
I am trying to open a file, skip the first 6 lines (headers) and extract data from the rest of the lines in the file. Here is the code:
%%Declarations
targetinfo(1000)=struct('distance', 0, 'speed', 0, 'angle', 0, 'rcs', 0);
i=1;                    %index
count=0;                %file size counter
[fid, message]=fopen('log.asc','r');   %open log file
%%Read file and extract relevant data
if fid==-1
    disp('Error')
else
    for k=1:6
        header=fgetl(fid);             %skip headers
    end
    while ~feof(fid)
        line=fgetl(fid);
        if line(16)=='S' || line(13)=='C' || line(1)=='T'       %remove control and status signals
            continue;
        end
        id=str2num(line(16:18));
        line=line(41:63);
        line=line(~isspace(line));
        if id==100
            canstatus=hex2dec(line(1:2));
            targetcount=hex2dec(line(3:4));
            canchannel=hex2dec(line(9:10));
        else
            targetinfo(i).distance=hex2dec(line(1:4));
            targetinfo(i).speed=hex2dec(line(5:8));
            targetinfo(i).angle=hex2dec(line(9:12));
            targetinfo(i).rcs=hex2dec(line(13:16));
        end
        count=count+1;                              %increase file size counter
        i=i+1;                                      %increase index
        fclose(fid);                                %close file
    end
end
I am getting the error I have specified in the title. The value of fid returned is not -1 (it is 4 at the moment) and I do have access to the file, since I can open it in Notepad to view its contents.
I am not opening and closing the file multiple times, just once. Is there any reason I'm missing out?
Thank you for your help.

Best Answer

hi,
you are closing the file in while loop and trying to access it again. use fclose() after you encountered feof
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