Re: detecting file types

Grant Edwards <grante@xxxxxxxx> writes:

On 2006-02-08, dagecko <dagecko@xxxxxxx> wrote:

I read it quickly, but in fact this was not what I was looking
for. I needed a way to detect, in a program made in C/C++, if
a file is a binary one or a simple ascii one.

1) Do a bitwise or of all the bytes in the file.

2) If bit 7 is set in the result, it's not an ASCII file.

3) If bit 7 is not set in the result, it _might_ be an ASCII
file. Or it might be a binay file that doesn't have any
bytes with bit 7 set.

If you know what language the ASCII is supposed to be, you
could look at the frequency distributions of individual
characters to give you a better idea if a file is really ASCII
or if it's a degenerate binary file.

Looking for non-printable characters < 0x20 is also a good idea.

--
Måns Rullgård
mru@xxxxxxxxxxxxx
.

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