G.Franzkowiak wrote:
Scott David Daniels schrieb:
franzkowiak wrote:
I've read some bytes from a file and just now I can't interpret 4
bytes in this dates like a real value. An extract from my program:
def l32(c):
return ord(c[0]) + (ord(c[1])<<8) + (ord(c[2])<<16) +
(ord(c[3])<<24)
...
value = l32(f.read(4)) <--- 3F 8C CC CD should be 1.11
OK, here's the skinny (I used blocks & views to get the answer):
import struct
bytes = ''.join(chr(int(txt, 16)) for txt in '3F 8C CC CD'.split())
struct.unpack('>f', bytes)
I was suspicious of that first byte, thought it might be an exponent,
since it seemed to have too many on bits in a row to be part of 1.11.
-Scott David Daniels
[EMAIL PROTECTED]
Ok, I the string exist with "mystr = f.read(4)" and the solution for
this case is in your line "struct.unpack('>f', bytes)"
But what can I do when I want the interpret the content from the Integer
myInt (*myInt = 0x3F8CCCCD) like 4-byte-real ?
This was stored with an othes system in a binary file to
CD CC 8C 3F and now is it in python in value. The conversion is not
possible. It's right... one of this bytes is an exponent.
I want copy the memory content from the "value address" to "myReal
address" and use print "%f" %myReal.
Is myReal then the right format ?
What can I do with python, in FORTH is it simple
( >f f. )
gf
If you really want to do this kind of byte fiddling:
http://members.dsl-only.net/~daniels/block.html
Then:
from block import Block, View
b = Block(4) # enough space for one float (more is fine)
iv = View('i', b) # getting to it as an integer
fv = View('f', b) # same memory as floating point
iv[0] = 0x3F8CCCCD # Here is a sample just using the integer
print fv[0]
On an Intel/Amd/Generic "PC" machine, you should get 1.1
-Scott David Daniels
[EMAIL PROTECTED]
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