[Tutor] reading binary files
alan.gauld at btinternet.com
Mon Feb 2 14:38:46 CET 2009
<etrade.griffiths at dsl.pipex.com> wrote>
> I am trying to read data from a file that has format
> item_name num_items item_type items ....
> TIME 1 0.0
> DISTANCE 10 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0
Where is the item_type?
> I can read this if the data are in ASCII format using
> in_file = open("my_file.dat","r")
> data1 = in_file.read()
> tokens = data1.split()
It might be easier to process line by line using readline
or readlines rather than read but otherwise, ok so far...
> and then stepping through the resulting list but the data
> also appear in the same format in a binary file.
When you say a binary file do you mean an ASCII file
encoded into binary using some standard algorithm?
Or do you mean the data is binary so that, for example,
the number 1 would appear as 4 bytes? If so do you
know how strings (the name) are delimited? Also
how many could be present - is length a single or
multiple bytes? and are the reors fixed length or
variable? If variable what is the field/record separator?
You may need to load the file into a hex editor of debugger
to determine the answers...
Having done that the struct module will allow you to read
You can see a basic example of using struct in my
tutorial topic about handling files.
Author of the Learn to Program web site
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