7bit ASCII out of 4 byte value

Hi guys

I'm currently writing a program that reads EXIF information out of NEF files (Nikon DSLR Raw format). It's based on the TIFF 6.0 definition.

My probleme is that in the documentation of TIFF it says that the Value of a IFD Entry can be a ASCII value BUT it's only 7bit long since the last bit is NUL. The Value block is 4 byte long and contains several characters at once. Now i tried this:

Code:

unsigned char Text[10];
for (int a = 0; a < Count; a++)
{
    fread(&Text[a], 1, 1, pFile);
}
cout << "Value: " << Text << endl;

Count is the number of characters
pFile is the File i've opened

When i run the programm it prints nothing as Value so the output is
"Value: "

My question is how do i get the characters out of the binary strip?

Thanks in advance

Patrick

You said they can be ASCII values, but that doesn't mean that they are printable characters. If you want to see the values of the bytes, you can print them as integers:

Code:

unsigned char Text[10];
for (int a = 0; a < Count; a++)
{
    fread(&Text[a], 1, 1, pFile);
    cout << "Value: " << (unsigned int)Text[a] << " " << endl;
}

Then you can look up the values on an ascii chart.

thank you for your reply you actually brought me to the solution.

The field is maximum 4 byte big and if the value is bigger the value field contains a offset to the actual value. since the counter was 10 it couldn't fit into that 4 byte field. when reading the field as offset and then apply the read-loop to this offset i get the value that is expected.