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From: Dennis Lee Bieber <wlfraed@ix.netcom.com>
Newsgroups: comp.lang.python
Subject: Re: Problems using struct pack/unpack in files, and reading them.
Date: Fri, 13 Nov 2015 19:46:16 -0500
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On Fri, 13 Nov 2015 14:20:45 -0500, kent nyberg <kent@z-sverige.nu>
declaimed the following:



>    tmp = place_to_read.read()[RegisterAX:calcsize('HH')]

	You've just read the ENTIRE FILE, and only kept whatever "RegisterAX"
represents to the size of the structure.

	If "RegisterAX" is supposed to indicate "where to start", you probably
need to be using

		[RegisterAX:RegisterAX+calcsize("HH")]

	Though you probably really need to be performing a seek() on the file
first to locate the start of what you want to read

	place_to_read.seek(RegisterAX)	#check the syntax for 
										#from start of file
	tmp = place_to_read.read()[:calcsize("HH")]

	But it may be even better to just read the desired number of bytes...

	tmp = place_to_read.read(calcsize("HH"))	#still need the seek()
-- 
	Wulfraed                 Dennis Lee Bieber         AF6VN
    wlfraed@ix.netcom.com    HTTP://wlfraed.home.netcom.com/