CODEWITHSUNDEEP
go
sourcey
sourcey

Reputation: 2691

Replace a line in text file Golang

How do I replace a line in a text file with a new line?

Assume I've opened the file and have every line in an array of string objects i'm now looping through

//find line with ']'
    for i, line := range lines {

        if strings.Contains(line, ']') {


            //replace line with "LOL"
            ?
        }
    }

Upvotes: 27

Views: 42458

Answers (1)

DallaRosa
DallaRosa

Reputation: 5825

What matters here is not so much what you do in that loop. It's not like you're gonna be directly editing the file on the fly.

The most simple solution for you is to just replace the string in the array and then write the contents of the array back to your file when you're finished.

Here's some code I put together in a minute or two. It properly compiles and runs on my machine.

package main

import (
        "io/ioutil"
        "log"
        "strings"
)

func main() {
        input, err := ioutil.ReadFile("myfile")
        if err != nil {
                log.Fatalln(err)
        }

        lines := strings.Split(string(input), "\n")

        for i, line := range lines {
                if strings.Contains(line, "]") {
                        lines[i] = "LOL"
                }
        }
        output := strings.Join(lines, "\n")
        err = ioutil.WriteFile("myfile", []byte(output), 0644)
        if err != nil {
                log.Fatalln(err)
        }
}

There's a gist too (with the same code) https://gist.github.com/dallarosa/b58b0e3425761e0a7cf6

Upvotes: 47

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