<etrade.griffi...@dsl.pipex.com> wrote
I have attached an example of the file in ASCII format and the
equivalent unformatted version.
Comparing them in vim...
It doesn't look too bad except for the DATABEGI / DATAEND message
format.
That could be tricky to unravel but we have no clear format for MESS.
But I assume that all the stuff between BEG and END is supposed to
be effectively nested?.
it gets to a data item that has no additional associated data,
then seems to have got 4 bytes ahead of itself.
You are creating a format string of >0d but I'm not sure how struct
behaves with zero lenths...
HTH,
Alan G.
==============================
# Test function to write/read from unformatted files
import sys
import struct
# Read file in one go
in_file = open("test.bin","rb")
data = in_file.read()
in_file.close()
# Initialise
nrec = len(data)
stop = 0
items = []
# Read data until EOF encountered
while stop < nrec:
# extract data structure
start, stop = stop, stop + struct.calcsize('4s8si4s8s')
vals = struct.unpack('>4s8si4s8s', data[start:stop])
items.extend(vals)
print stop, vals
# define format of subsequent data
nval = int(vals[2])
if vals[3] == 'INTE':
fmt_string = '>i'
elif vals[3] == 'CHAR':
fmt_string = '>8s'
elif vals[3] == 'LOGI':
fmt_string = '>i'
elif vals[3] == 'REAL':
fmt_string = '>f'
elif vals[3] == 'DOUB':
fmt_string = '>d'
elif vals[3] == 'MESS':
fmt_string = '>%dd' % nval
else:
print "Unknown data type ... exiting"
print items
sys.exit(0)
# extract data
for i in range(0,nval):
start, stop = stop, stop + struct.calcsize(fmt_string)
vals = struct.unpack(fmt_string, data[start:stop])
items.extend(vals)
# trailing spaces
if nval > 0:
start, stop = stop, stop + struct.calcsize('4s')
vals = struct.unpack('4s', data[start:stop])
# All data read so print items
print items
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_______________________________________________
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http://mail.python.org/mailman/listinfo/tutor
