= Go BufIO =

The '''`bufio`''' package provides buffered I/O. 

<<TableOfContents>>

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== Usage ==



=== Reader ===



=== Scanner ===

A `Scanner` is used to read a file in steps of 'tokens'. Calls to `Scan()` return the next token. A `SplitFunc` type function is used to tokenize a file. The default function splits a file into lines with line termination stripped.

Scanning stops unrecoverably at EOF, an error, or a too-large token. If a more tolerant file reader is called for, use `Reader` instead.

As an example:

{{{
import (
    "strings"
    "regexp"
    "bufio"
    "fmt"
    "os"
)

var Pattern = regexp.MustCompile(`PING`)

func main() {
    count := 0

    // Initialize the Builder
    var content strings.Builder

    // Initialize the Scanner using STDIN
    scanner := bufio.NewScanner(os.Stdin)

    // Loop over scanned lines
    for scanner.Scan() {
        line := scanner.Text()

        matches := Pattern.FindAllStringIndex(line, -1)

        // Build lines
        for i := len(matches)-1; i >= 0; i-- {
            line = line[:matches[i][0]] + fmt.Sprintf("[%d]", count+i) + line[matches[i][1]:]
        }
        content.WriteString(line)
        content.WriteString("\n")

        count += len(matches)
    }

    // Check for scanner errors
    if err := scanner.Err(); err != nil {
        fmt.Println(err)
    }

    // Print to STDOUT
    fmt.Printf(content.String())
}
}}}

{{{
$ cat test
Hello, this is PING your PING friend.
I am PING testing your work. PING.
PING PING PING test PING.

$ cat test | ./scan-and-build
Hello, this is [0] your [1] friend.
I am [2] testing your work. [3].
[4] [5] [6] test [7].

}}}



=== Writer ===

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== See also ==

[[https://pkg.go.dev/bufio|bufio package]]



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