You can imitate the C idiom in Python.
To read a buffer up to max_size number of bytes, you can do this:
with open(filename, 'rb') as f:
while True:
buf = f.read(max_size)
if not buf:
break
process(buf)
Or, a text file line by line:
# warning -- not idiomatic Python! See below...
with open(filename, 'rb') as f:
while True:
line = f.readline()
if not line:
break
process(line)
You need to use while True / break construct since there is no eof test in Python other than the lack of bytes returned from a read.
In C, you might have:
while ((ch != '\n') && (ch != EOF)) {
// read the next ch and add to a buffer
// ..
}
However, you cannot have this in Python:
while (line = f.readline()):
# syntax error
because assignments are not allowed in expressions in Python (although recent versions of Python can mimic this using assignment expressions, see below).
It is certainly more idiomatic in Python to do this:
# THIS IS IDIOMATIC Python. Do this:
with open('somefile') as f:
for line in f:
process(line)
Update: Since Python 3.8 you may also use assignment expressions:
while line := f.readline():
process(line)