CODEWITHSUNDEEP
python-2.7arrayslong-integer
FredFury
FredFury

Reputation: 2511

Reading 4 bytes of data as a Long with Python 2

I have four bytes which I need to read as a long.

When I read my file, I read the following bytes: 

['\x10', '\xef', '\xf1', '\xea']

According to my file format description, these four bytes represent a long.

How would I convert these bytes to a long with Python?

Additionally: Would one use a similar method to convert 2 bytes into a Short?

Here is example code of how I read my file:

source = "test.whatever"
print "Loading file:", source;
data = []   
f = open(source, "rb")
counter = 0;

#Let's load the data here:
try:
    byte = f.read(1) #skip the first byte according to my file
    while byte != "": 
        byte = f.read(1)
        data.append(byte)  #read every byte into an array to work on later
        counter = counter + 1

finally:
    f.close()
print "File loaded."
print counter

Upvotes: 1

Views: 2040

Answers (1)

John Zwinck
John Zwinck

Reputation: 249303

import struct
struct.unpack('>l', ''.join(ss))

I chose to interpret it as big-endian, you need to decide that yourself and use < instead if your data is little-endian.

If possible, use unpack_from() to read the data directly from your file, instead of using an intermediate list-of-single-char-strings.

Upvotes: 3

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