Golang : convert(cast) bytes to string


Tags : golang convert bytes string three-dots

Encounter a problem when helping out a co-worker today to read in data generated by another program. To make it short, the data is in the form of array of bytes and the objective is to convert the bytes into string. The problem is that the length of the given data is dynamic and we need to create a program that can handle the dynamic length.

Typically, the program should look something like 1st program below

1st program :

 package main

 import "fmt"

 func main() {
  src := [10]byte{'h', 'e', 'l', 'l', 'o', ' ', 'w', 'o', 'r', 'l', 'd'}
  fmt.Println(len(src), src)

  dst := string(src[:])
  fmt.Println(len(dst), dst)
 }

and running this program will generate error array index 10 out of bounds [0:10] and to fix the error.... a programmer will typically just increase the array size.... which in turn... it will work ... but also generate trailing zeros 20 [104 101 108 108 111 32 119 111 114 108 100 0 0 0 0 0 0 0 0 0].

What if there is a incoming array of higher values ? Then the error will appear again.

In Golang, there is a better way to handle this kind of dynamic length situation. We will use the three dots to tell the compiler to figure out the length of the array during run time.

2nd program :

 package main

 import "fmt"

 func main() {
  src := [...]byte{'h', 'e', 'l', 'l', 'o', ' ', 'w', 'o', 'r', 'l', 'd'}
  fmt.Println(len(src), src)

  dst := string(src[:])
  fmt.Println(len(dst), dst)
 }

Output :

11 [104 101 108 108 111 32 119 111 114 108 100]

11 hello world

Hope this will assist you in developing a more robust program.

  See also : Golang : automatically figure out array length(size) with three dots



Tags : golang convert bytes string three-dots

By Adam Ng

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