file.readlines() Read all lines
Last updated: 2026-09-22
file.readlines() Read all lines
file.readlines() returns a list of all lines, keeping the trailing newlines.
| Category | File Methods |
|---|---|
| Kind | Built-in Type Method |
| Python Version | all |
📝 Syntax
file.readlines()⚙️ Parameters
| hint Optional | Expected byte count hint; -1 reads all lines.（Default：-1） |
|---|
Returns：A list of all lines, each keeping its trailing newline.
Mutates the original：No (returns a new object)
💥 Raises
OSError— Raised when the file is closed or on I/O errors.
▶ Example
Edit the code, press Run, and see the result in the output panel:
Output：
['a\n', 'b\n', 'c\n']💡 Related Cases
More case studies coming soon — check back later.
❓ FAQ
QWhat does readlines() return?
AA list of all lines, each keeping its trailing newline.
QWhat is the difference from for line in f?
Areadlines() loads the whole file into memory at once (use with care for large files); for line in f reads lazily line by line and uses less memory.
QWhat is the hint parameter for?
AIt is only a hint of the "expected byte count" for the internal buffer and is not guaranteed to be exact; you generally do not need to care about it.
QHow do I strip the newline from each line?
AProcess each line with line.rstrip('\n') or str.strip().
