Stage 3 · Build
Standard Library for Operations
Streaming I/O
io.Reader, io.Writer, bufio.Scanner limits, io.Pipe, and copying large outputs safely.
7 min readGo for SREBuild
io.Reader and io.Writer
io.Reader and io.Writer are the fundamental interfaces for I/O in Go. Nearly everything that reads or writes data implements one of these interfaces: files, network connections, HTTP bodies, buffers, and pipes.
Gothe-io-interfaces.go
18 linesLn 1, Col 1Go
The io interfaces are the foundation of Go I/O. They compose — io.ReadCloser combines Reader and Closer. This composition means any function that takes io.Reader works with files, network connections, and buffers.
io.Copy and io.CopyN
Gocopying-data.go
52 linesLn 1, Col 1Go
io.Copy buffers automatically. io.CopyN limits bytes. For progress reporting, read in a loop and track bytes written. Always check both read and write errors. io.EOF signals end of data.
bufio.Scanner
Gobufio.scanner-usage.go
46 linesLn 1, Col 1Go
bufio.Scanner reads input line by line. Buffer sets the maximum token size — increase it for long lines. Split functions control tokenization: ScanLines, ScanWords, ScanRunes, or custom functions.
io.Pipe
Goio.pipe-for-goroutine-communication.go
44 linesLn 1, Col 1Go
io.Pipe creates a synchronous pipe. Writes to pw block until pr reads. This is useful for streaming data between goroutines without buffering. The pipe is synchronous — backpressure is automatic.
io.MultiReader
Gocombining-readers.go
40 linesLn 1, Col 1Go
io.MultiReader concatenates readers. io.TeeReader writes to a writer while reading. io.LimitReader limits bytes read. These compose to create powerful data pipelines.
Limiting Readers
Goreader-limits-and-timeouts.go
47 linesLn 1, Col 1Go
io.LimitReader prevents reading too much data. ContextReader checks for cancellation before reading. Timeout reader combines io.ReadAll with time.After for read deadlines. These patterns prevent hanging reads.
Use io.Copy for streaming
io.Copy buffers data automatically and handles partial reads/writes. It is more efficient than reading entire files into memory. Use it for file copying, network streaming, and HTTP body processing.
Mark this lesson complete to store local progress and unlock a cleaner resume path the next time you visit.