file.read() Read file content
Last updated: 2026-09-22
file.read() Read file content
file.read(size=-1) reads the file content; omit size to read everything.
| Category | File Methods |
|---|---|
| Kind | Built-in Type Method |
| Python Version | all |
📝 Syntax
file.read()⚙️ Parameters
| size Optional | Number of bytes/chars to read; -1 reads to EOF.（Default：-1） |
|---|
Returns：The read content: str in text mode, bytes in binary mode.
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：
hello
world💡 Related Cases
More case studies coming soon — check back later.
❓ FAQ
QWhat does read() with no argument read?
AThe entire file up to the end. In text mode it returns str, in binary mode it returns bytes.
QHow do I read a large file?
ARead in chunks with size: f.read(1024) reads at most 1024 characters/bytes each time; an empty return means the end has been reached.
QWhat is read out of an empty file?
AThe empty string '' in text mode and b'' in binary mode, without raising an error.
QWhat happens when reading twice in a row?
AThe second read continues from the previous position. To reread the whole file, first call f.seek(0) to return to the start.
