I got a question that’s puzzling me. Am new to Ruby but programming for
decades. Here’s the problem. This apparently simple loop reads 396 bytes
of a file and no more. The actual file is 1.5KB and I can display it
easily in a hex dumper. The bytes Ruby has read are all correct. It just
seems to stop after 396 bytes. Any idea what’s wrong or where I should
be looking?
Many thanks in advance,
JK Daniels
code >>>
if ARGV[0] == nil
puts( “\n” + $help )
else
i = 0
tfm = File.open( ARGV[0] )
tfm.each_byte{ |c| i = i + 1; printf( “%d: %X\n”, i, c ) }
if tfm.eof
puts “at eof” else puts “not at eof”
end
end
<<< end code <<<
This outputs the first 396 bytes and then state it’s at EOF. If it makes
any difference, the last three bytes it reads are (all hex): C0 A4 00
and the next three (unread) bytes in the file are: 1A C0 B5
I got a question that’s puzzling me. Am new to Ruby but programming for
decades. Here’s the problem.
Welcome to the red world
This apparently simple loop reads 396 bytes
<<< end code <<<
This outputs the first 396 bytes and then state it’s at EOF. If it makes
any difference, the last three bytes it reads are (all hex): C0 A4 00
and the next three (unread) bytes in the file are: 1A C0 B5
Hmm you are not reading a binary file under windows by any chance?
In that case File.open needs a mode “rb”.
Anyway the ruby way to do what you want is more like this
File.open ARGV.first, “rb” do # I would put paranthesis, but just to
demonstrate the
# various possibilities
|file|
i = 0
file.each_byte {
|c|
i += 1
puts “%d:%X” % [ i, c ]
}
end
puts “at eof ;)”
This outputs the first 396 bytes and then state it’s at EOF. If it makes
any difference, the last three bytes it reads are (all hex): C0 A4 00
and the next three (unread) bytes in the file are: 1A C0 B5
I tested this on a file that was 29,184 bytes - it worked fine.
Could it be something in your data or environment?
Thank you Guy, Steven, and Robert for solving the problem. I appreciate
it. Never occurred to me it could be a control-z problem. Robert, thanks
especially for showing the same code using typical Ruby metaphors. This
also helps a lot.