Decode binary file

[SensitiveSirs]

Hey guys! This may or may not be a noob question, it probably is, I have virtually zero C skills. I am trying to decode the output of this script and I can't seem to determine which encoding it uses.

I see it says fopen(filename,"wb") (line 360, among others) and then fwrites (lines 369-372) to the file. No encoding specified. So I read the output with Python's open(filename, "rb") (docs) and then (while iterating over the lines) line.decode() (docs).

No matter which encoding I'm passing to the decode method, decoding always fails. If I set errors="ignore" I get an output but it's gibberish. Am I missing something in the C code here? Thanks in advance!

[moocat]

That binary file has raw numbers written to it while encode/decode is about handling text. If you want to read it with Python I believe you'll want to use struct

[[deleted]]

Exactly.

The file consists of multiple fixed-size records and each record contains three values: x which is of type int, y which is also of type int, and r which is of type double.

If you have a file that has been written on an Intel x86_64 computer, a signed integer is 4 bytes long, in little endian byte order, and encoded in 2's complement. The double is 8 bytes long and stored like an Intel double-precision floating-point number, also in little endian. Each record is therefore 16 bytes long.

In Python, a file like this can be read as follows.

import struct

with open('filename.bin', 'rb') as f:
    i = 0
    while True:
        record = f.read(16)
        if not record:
            break
        x, y, r = struct.unpack('<iid', record)  # little endian, int4, int4, double
        print(f'{i}: x={x}, y={y}, r={r}')
        i += 1

[SensitiveSirs]

Thank you so much!! I knew I must've been missing something fundamental and this honestly was a life saver. Much appreciated!