Golang : Reverse text lines or flip line order example




Problem:

You are given lines of text and you need to reverse the lines order before encrypting the text. Reversing or scrambling the lines of text order can be useful in situation when you want extra layer of protection against decryption program. For example, from

abc

def

to

def

abc

How to do that?

Solution:


 package main

 import (
 "fmt"
 "strings"
 )

 func main() {
 // originalOrder := `abc
 //def
 //ghi
 //jkl
 //mno
 //pqr
 //stu
 //vwx
 //yz`

 originalOrder := `Lorem ipsum dolor sit amet, consectetur adipiscing elit.
 Praesent porttitor nulla vitae interdum fermentum. Ut in vulputate neque.
 Praesent luctus lacus a dolor tempus pellentesque. Cras sit amet urna eu augue suscipit eleifend.
 Mauris mollis pharetra faucibus. Phasellus eu massa quam.
 Nunc id metus placerat neque feugiat commodo.`

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

 fmt.Println("Before :\n ", originalOrder)

 reverseOrderSlice := []string{}

 // https://www.socketloop.com/tutorials/golang-how-to-reverse-slice-or-array-elements-order
 //reverse the elements in lines slice
 for i := range lines {
 n := strings.TrimSpace(lines[len(lines)-1-i])
 reverseOrderSlice = append(reverseOrderSlice, n+"\n")
 }

 fmt.Println("=============================================")

 // but we want the end result to be lines
 toLines := fmt.Sprintf("%v", reverseOrderSlice)
 // remove the prefix [ and suffix ] leftover
 toLines = toLines[1 : len(toLines)-1]

 fmt.Println("After :\n ", toLines)

 }

Output:

 Before :
 Lorem ipsum dolor sit amet, consectetur adipiscing elit.
 Praesent porttitor nulla vitae interdum fermentum. Ut in vulputate neque.
 Praesent luctus lacus a dolor tempus pellentesque. Cras sit amet urna eu augue suscipit eleifend.
 Mauris mollis pharetra faucibus. Phasellus eu massa quam.
 Nunc id metus placerat neque feugiat commodo.
 =============================================
 After :
 Nunc id metus placerat neque feugiat commodo.
  Mauris mollis pharetra faucibus. Phasellus eu massa quam.
  Praesent luctus lacus a dolor tempus pellentesque. Cras sit amet urna eu augue suscipit eleifend.
  Praesent porttitor nulla vitae interdum fermentum. Ut in vulputate neque.
  Lorem ipsum dolor sit amet, consectetur adipiscing elit.

References:

https://www.socketloop.com/tutorials/golang-how-to-reverse-slice-or-array-elements-order

https://www.socketloop.com/tutorials/golang-convert-lines-of-string-into-list-for-delete-and-insert-operation

  See also : Golang : How to reverse slice or array elements order





By Adam Ng

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