Records, Text Files and Binary Files

A file can contain multiple logical records, each with fields describing an entity. In a text format, separators, quoting and line boundaries need agreed meanings. Splitting every line at a comma fails when a quoted field itself contains a comma; use a format-aware parser for formats such as CSV.

Text files store encoded characters, not abstract Python objects. Reading "42" usually produces text that must be converted if a numerical value is needed. Specify an encoding such as UTF-8 and distinguish an empty field, a missing field and a legitimate zero.

A read operation obtains existing data; writing with a truncating mode can replace existing content, while append adds at the end. A context manager in Python closes the file even when control leaves the block unexpectedly. Check that the path and permissions match the intended task.

A binary file stores bytes interpreted according to a schema or application format. It may compactly represent fixed-width values or media, but byte order, widths and record boundaries must be known. Binary does not mean encrypted, and text is also ultimately represented by bits.

Validate a record’s shape and convert its fields before relying on it. A malformed record should have a defined response rather than silently becoming plausible but incorrect data. File-not-found and invalid-format errors have different causes and may require different recovery paths.

For a fixed-size binary record, an offset can identify its position when the format specifies the record size. Variable-length text records do not generally permit the same simple multiplication. Test both a round trip and failure cases: write known data, read it back and compare values and types.

from io import StringIO, BytesIO
text_file = StringIO("Ada,42\n")
name, score_text = text_file.readline().strip().split(",")
score = int(score_text)
binary_file = BytesIO(bytes([0, 42, 255]))
print(name, score, list(binary_file.read()))

from pathlib import Path
from tempfile import TemporaryDirectory

with TemporaryDirectory(prefix="kepler-example-") as folder:
    text_path = Path(folder) / "scores.txt"
    with text_path.open("w", encoding="utf-8") as handle:
        handle.write("Ada,42\n")
    with text_path.open("r", encoding="utf-8") as handle:
        print(handle.read().strip())

    binary_path = Path(folder) / "values.bin"
    with binary_path.open("wb") as handle:
        handle.write(bytes([7, 8]))
    with binary_path.open("rb") as handle:
        print(list(handle.read()))

Attempt the task before opening its worked response. Record each change of state, explain the rule used, and check the result against the original requirements. Code examples labelled Python 3 use that language’s conventions; pseudocode states its own assumptions.