Golang : Chunk split or divide a string into smaller chunk example


You need a function in Golang that are similar to PHP's chunk_split() function that can split a string into smaller chunks. It is commonly used in converting base64 encoded string to match RFC 2045 semantics. Such as line-breaking base64 encoded lines at 76 characters.

Excerpt from https://www.ietf.org/rfc/rfc2045.txt

(5) Encoded lines must not be longer than 76 characters, not counting the trailing CRLF. If longer lines are found in incoming, encoded data, a robust implementation might nevertheless decode the lines, and might report the erroneous encoding to the user.


This code example below should do the job on dividing a string into smaller chunks.

 package main

 import (

 func chunkSplit(body string, limit int, end string) string {

 var charSlice []rune

 // push characters to slice
 for _, char := range body {
 charSlice = append(charSlice, char)

 var result string = ""

 for len(charSlice) >= 1 {
 // convert slice/array back to string
 // but insert end at specified limit

 result = result + string(charSlice[:limit]) + end

 // discard the elements that were copied over to result
 charSlice = charSlice[limit:]

 // change the limit
 // to cater for the last few words in
 // charSlice
 if len(charSlice) < limit {
 limit = len(charSlice)


 return result


 func main() {
 before := "this is a long string that needs to be chunked into smaller chunks"

 // chunk after 30 characters and append with newline
 // for RFC 2045, change limit from 30 to 76
 after := chunkSplit(before, 30, "\n")

 fmt.Println("Before :\n", before)
 fmt.Println("After :\n", after)


Before :

this is a long string that needs to be chunked into smaller chunks

After :

this is a long string that nee

ds to be chunked into smaller






  See also : Golang : Warp text string by number of characters or runes example

By Adam Ng

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