Writing and reading a binary file with python #Python

1. Requirements

Ubuntu16.04
Python3.x

2. Refference

https://docs.python.org/ja/3/library/struct.html

3. Sample codes (main.py)

function

import struct                                                                                                    

'''
  Charactor, Byte-order
  @,         native
  <,         little endian
  >,         big endian

  Format, C-type,         Python-type, Size[byte]
  c,      char,           byte,        1
  b,      signed char,    integer,     1
  B,      unsigned char,  integer,     1
  h,      short,          integer,     2
  H,      unsigned short, integer,     2
  i,      int,            integer,     4
  I,      unsigned int,   integer,     4
  f,      float,          float,       4
  d,      double,         float,       8
'''

def bwrite(data, filename):
  with open(filename, "wb") as f:
    for x in data:
      f.write(struct.pack('b', x)) # 1byte

def bread(filename):
  with open(filename, 'rb') as f:
    bdata = []
    while True:
      bytes = f.read(1)
      if bytes == b'':
        break
      else:
        bdata.append(struct.unpack('b', bytes)[0]) # 1byte
  hdata = [hex(x) for x in bdata]
  return bdata, hdata

def main():
  bwrite([0x00, 0x11, 0x22, 0x33], 'binary.dat')
  bdata, hdata = bread('binary.dat')
  print('bdata', bdata)
  print('hdata', hdata)

if __name__ == "__main__":
  main()

4. Results

$ python main.py 
bdata [0, 17, 34, 51]
hdata ['0x0', '0x11', '0x22', '0x33']

$ hexdump binary.dat 
0000000 1100 3322                              
0000004

Thank you.
last-samurai