mirror of
https://github.com/rust-lang/rustlings.git
synced 2026-08-14 14:26:56 +00:00
68f8369cb4
- file_io3: replace the hardcoded expected file size (117) with SAMPLE_TEXT.len(), so the check is derived from the actual content instead of an unexplained magic number. - file_io3: use create_dir_all instead of create_dir, and add a sample_file_path() helper shared by main/create_required_files/ file_cleanup to avoid three separate ad-hoc path constructions. - file_io1/file_io2: hoist the sample text into a SAMPLE_TEXT constant used by both the exercise and its solution, removing duplicated literals. No behavioral change: all three solutions were rebuilt and run locally, producing identical output (file size still 117, permissions still non-readonly) with no leftover files.
File IO
Rust provides several file I/O functions in the standard library. Buffered reads and writes provide better performance by reducing the number of underlying system calls.
Learning goals
- file_io1 — Read an entire file into memory with
fs::read_to_stringand handle theResultit returns instead of unwrapping blindly, so you get comfortable with the basic "open, read, handle the error" pattern that most file I/O in Rust builds on. - file_io2 — Wrap a
Filein aBufReaderto read it line by line and aBufWriterto write the transformed output, so you understand why buffering matters for I/O performance and howBufRead::lineslets you process input incrementally instead of loading it all at once. - file_io3 — Build a path with
PathBuf, then call.metadata()to inspect properties like creation time, size, and permissions, so you can work with the filesystem safely across platforms without hardcoding path separators.
Further information
Here is the documentation for these functions in the standard library.