How Can I Efficiently Read Specific Lines from a File in Go?

Efficiently Reading Specific Lines from a File in Go

When working with files, it's often necessary to read specific lines. In Go, there are various approaches to achieve this, but one of the most straightforward and efficient is using the bufio.Scanner type.

The ReadLine function provided in the question uses bufio.Scanner to iterate through the lines of a file. However, some optimizations can be made for improved efficiency.

The modified function below leverages the fact that bufio.Scanner returns both the line as a string and an error:

<code class="go">func ReadLine(r io.Reader, lineNum int) (line string, lastLine int, err error) {
    sc := bufio.NewScanner(r)
    for sc.Scan() {
        lastLine++
        if lastLine == lineNum {
            return sc.Text(), lastLine, sc.Err()
        }
    }
    return line, lastLine, io.EOF
}</code>

This optimization eliminates the need for an additional call to sc.Err() when returning the result, improving performance slightly.

The original ReadLine function provides a simple and effective way to read specific lines from a file in Go. With the optimization described above, it offers improved efficiency by reducing unnecessary function calls and memory allocations.

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