Fscanln

Fscanln is a function in the Go standard library, part of the fmt package. It reads formatted input from an input source and assigns the scanned values to the provided destinations. The scanning uses whitespace as separators and stops when a newline is encountered, with the newline being consumed but not assigned. The function signature is func Fscanln(r io.Reader, a ...interface{}) (n int, err error). It returns the number of successfully assigned values and an error value if one occurred.

Behavior and usage notes: Fscanln reads from a reader until a newline is found, filling the destination variables in order. If the end of the input is reached before a newline, it returns io.EOF (along with any values that were scanned). If a token cannot be assigned to a destination, an error is returned. Because it stops at a newline, Fscanln is well suited for line-oriented input where each line contains a fixed number of fields.

Comparison with related functions: Fscanln differs from fmt.Fscan in that Fscan reads across lines without stopping at a newline, while Fscanln strictly terminates after processing a line. This makes Fscanln appropriate when your input is organized by lines and you want to enforce one line per scan operation.

Example usage (conceptual): reading a line from standard input into a string and an integer, one line per call, and handling the number of successfully scanned values and potential errors. Fscanln is a practical tool for simple, line-based parsing in Go programs.