How to Read a File from a Specific Line Number Using Scanner in Go?

Mary-Kate Olsen
Release: 2024-11-06 15:03:03
Original
784 people have browsed it

How to Read a File from a Specific Line Number Using Scanner in Go?

Reading a File from a Specific Line Number Using Scanner

In Go, the bufio.Scanner package provides a convenient way to read files line by line. However, by default, Scanner does not offer a method to skip or read from a specific line number. To achieve this, we need to modify the default behavior of Scanner.

Extended Solution with Custom Token Spliter Function

We can extend the Scanner by creating a custom split function that determines the line boundaries and maintains the file position. Let's define a split function that returns the advance in bytes to the next line break and the line as a token:

func scanLinesWithPosition(data []byte, atEOF bool) (advance int, token []byte, err error) {
    advance, token, err = bufio.ScanLines(data, atEOF)
    return // Advance and Token are calculated
}
Copy after login

Next, we can use the Scanner.Split method to set our custom splitter function:

scanner := bufio.NewScanner(inputFile)
scanner.Split(scanLinesWithPosition)
Copy after login

Handling Line Position

With the custom split function in place, we can read lines while also maintaining the file position. Here's a modified version of your existing code:

// ... (Code from your post)

func main() {
    // ... (Code from your post)

    scanner := bufio.NewScanner(inputFile)
    scanner.Split(scanLinesWithPosition)

    var currentLine int
    for scanner.Scan() {
        currentLine++
        if currentLine > progress {
            fmt.Println(scanner.Text())
        }
    }

    // ... (Code from your post)
}
Copy after login

Now, the code reads lines, skips lines already processed (based on the progress variable), and maintains the current line number. By adjusting the progress value, you can control the starting line number.

The above is the detailed content of How to Read a File from a Specific Line Number Using Scanner in Go?. For more information, please follow other related articles on the PHP Chinese website!

source:php.cn
Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Latest Articles by Author
Popular Tutorials
More>
Latest Downloads
More>
Web Effects
Website Source Code
Website Materials
Front End Template
About us Disclaimer Sitemap
php.cn:Public welfare online PHP training,Help PHP learners grow quickly!