Reading binary file and looping over each byte

Question

In Python, how do I read in a binary file and loop over each byte of that file?

Answer 1

To sum up all the brilliant points of chrispy, Skurmedel, Ben Hoyt and Peter Hansen, this would be the optimal solution for processing a binary file one byte at a time:

with open("myfile", "rb") as f:
    while True:
        byte = f.read(1)
        if not byte:
            break
        do_stuff_with(ord(byte))

For python versions 2.6 and above, because:

• python buffers internally - no need to read chunks
• DRY principle - do not repeat the read line
• with statement ensures a clean file close
• 'byte' evaluates to false when there are no more bytes (not when a byte is zero)

Or use J. F. Sebastians solution for improved speed

from functools import partial

with open(filename, 'rb') as file:
    for byte in iter(partial(file.read, 1), b''):
        # Do stuff with byte

Or if you want it as a generator function like demonstrated by codeape:

def bytes_from_file(filename):
    with open(filename, "rb") as f:
        while True:
            byte = f.read(1)
            if not byte:
                break
            yield(ord(byte))

# example:
for b in bytes_from_file('filename'):
    do_stuff_with(b)