Writing Bytes to strings.builder prints nothing - string

Question

I am learning go and am unsure why this piece of code prints nothing
package main
import (
"strings"
)
func main(){
var sb strings.Builder
sb.WriteByte(byte(127))
println(sb.String())
}
I would expect it to print 127

Answer 1

You are appending a byte to the string's buffer, not the characters "127".
Since Go strings are UTF-8, any number <=127 will be the same character as that number in ASCII. As you can see in this ASCII chart, 127 will get you the "delete" character. Since "delete" is a non-printable character, println doesn't output anything.
Here's an example of doing the same thing from your question, but using a printable character. 90 for "Z". You can see that it does print out Z.
If you want to append the characters "127" you can use sb.WriteString("127") or sb.Write([]byte("127")). If you want to append the string representation of a byte, you might want to look at using fmt.Sprintf.
Note: I'm not an expert on character encoding so apologies if the terminology in this answer is incorrect.