Readline
Readline is an operation or API that reads the next line or line fragment from an input stream or file-like source.
The Quick Python Book, Fourth Edition
readline is a file-object method that reads and returns one line, including its terminating newline when present, or an empty string at end of file.
- How it is used
- Reads individual lines from opened files and supports sequential processing or simple line-counting loops.
- How deep it goes
- Defines returned line contents, successive reads, end-of-file behavior, memory caveats, and optional limits without detailing the reference signature.
- Examples
- Uses a with-open call, a repeated-read line counter, and sys.stdin.readline for terminal input.
- What you can do after
- Apply it via Python file objects to read lines, detect end of file, and process input incrementally.
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Learn AI-Assisted Python Programming, Second Edition
The readline method reads and returns the next line from a file-like object as text.
- How it is used
- Uses readline to inspect successive lines from an open file before processing records.
- How deep it goes
- Defines the method and demonstrates header and record retrieval, while deferring whole-file processing to a for loop.
- Examples
- Demonstrates readline with an NFL statistics CSV header and the first data row.
- What you can do after
- Apply readline in Python to inspect lines from an open file and prepare their contents for processing.
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Julia as a Second Language
readline is a Julia function that reads one line of text from an input stream.
- How it is used
- Reads keyboard, file, and other stream input one line at a time for simple text processing.
- How deep it goes
- Demonstrates line-by-line loops and stream types, while deferring more sophisticated CSV-reading techniques.
- Examples
- Uses pizza-sales.csv, keyboard input, and rocket-engines.csv to demonstrate line-oriented reading.
- What you can do after
- Apply it via Julia I/O objects to read files or keyboard lines and feed the resulting text into parsing workflows.
The Well-Grounded Rubyist, Fourth Edition
readline is a Ruby IO method that reads the next line from an input stream and raises an end-of-file error when no line is available.
- How it is used
- Reads line-oriented input and turns end-of-file into an exception that interactive or network programs can handle.
- How deep it goes
- Explains line reading, stream position, and EOFError handling, but stops short of implementation internals.
- Examples
- Demonstrates readline with Ruby file objects and a threaded TCP chat server.
- What you can do after
- Apply it in line-oriented file or socket loops, rescuing EOFError when stream closure requires cleanup.
Read how The Well-Grounded Rubyist, Fourth Edition explains readline →
Related concepts
- stream readerused by · A stream reader is an object or API component that reads data from a readable stream, synchronously or asynchronously.
- shell command historyused by · Shell command history is a chronological record of commands entered in an interactive command-line environment that can be recalled or searched.
- getscontrasts with · gets is a Ruby input method that reads the next line from a file or other input stream and returns nil at end of input.
- bufio.Readerused by · bufio.Reader is a Go buffered reader that wraps an io.Reader and supports efficient incremental and look-ahead reading.
- stringproduces · A string is a programming-language value representing an ordered sequence of characters or character units as text.
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