Golang : Join lines with certain suffix symbol example

For this tutorial,we will learn how to join lines of text into a string and also explore the option to ONLY join certain lines than match a given criteria. The situation that demands this kind of join lines utility is usually involve cleanly up raw text data files. For example, in the text data files, certain lines need to be joined if some lines end with : or + symbols.

The code example below demonstrates how to join lines by the default empty space, insert : symbol in between or only join the lines if a line has certain symbol as suffix.

Here you go!

 package main

 import (
 "fmt"
 "strings"
 )

 func JoinLines(input []string, joinBy string) string {
 return strings.Join(input, joinBy)
 }

 func OnlyJoinLines(input []string, onlyJoinBy string) string {

 var result []string

 var skipIndex int

 for k, v := range input {
 if strings.HasSuffix(v, onlyJoinBy) {
 // only join lines that match the criteria

 if k+1 >= len(input) {
 result = append(result, v+input[k]+"\n")
 skipIndex = k
 } else {
 result = append(result, v+input[k+1]+"\n")
 // after joining, mark the next index to skip
 skipIndex = k + 1
 }
 } else {
 if !(skipIndex > 0) {
 result = append(result, v+"\n")
 }
 // remember to reset back to 0
 skipIndex = 0
 }

 }

 return strings.Join(result, "")

 }

 func main() {
 lines := `line 1
  line 2
  line 3:
  line 4
  line 5:
  line 6
  line 7
  line 8+
  line 9`

 // turn lines into slice
 lineSlice := strings.Split(lines, "\n")

 result1 := JoinLines(lineSlice, " ")
 fmt.Println("RESULT 1 : ", result1)

 // join all lines with :
 result2 := JoinLines(lineSlice, ":")
 fmt.Println("RESULT 2 : ", result2)

 // ONLY join lines that have : symbol as suffix
 result3 := OnlyJoinLines(lineSlice, ":")
 fmt.Println("RESULT 3 : ", result3)

 // ONLY join lines that have + symbol as suffix
 result4 := OnlyJoinLines(lineSlice, "+")
 fmt.Println("RESULT 4 : ", result4)

 }

Output:

 RESULT 1 :  line 1  line 2  line 3:  line 4  line 5:  line 6  line 7  line 8+  line 9
 RESULT 2 :  line 1: line 2: line 3:: line 4: line 5:: line 6: line 7: line 8+: line 9
 RESULT 3 :  line 1
  line 2
  line 3: line 4
  line 5: line 6
  line 7
  line 8+
  line 9

 RESULT 4 :  line 1
  line 2
  line 3:
  line 4
  line 5:
  line 6
  line 7
  line 8+ line 9

Hope this helps and happy coding!

References:

https://www.socketloop.com/tutorials/golang-how-to-check-if-a-string-starts-or-ends-with-certain-characters-or-words

https://www.socketloop.com/tutorials/golang-scramble-and-unscramble-text-message-by-randomly-replacing-words