How to index characters in a Golang string?

Interpreted string literals are character sequences between double quotes "" using the (possibly multi-byte) UTF-8 encoding of individual characters. In UTF-8, ASCII characters are single-byte corresponding to the first 128 Unicode characters. Strings behave like slices of bytes. A rune is an integer value identifying a Unicode code point. Therefore,

package main

import "fmt"

func main() {
    fmt.Println(string("Hello"[1]))              // ASCII only
    fmt.Println(string([]rune("Hello, 世界")[1])) // UTF-8
    fmt.Println(string([]rune("Hello, 世界")[8])) // UTF-8
}

Output:

e
e
界

Read:

Go Programming Language Specification section on Conversions.

The Go Blog: Strings, bytes, runes and characters in Go

How about this?

fmt.Printf("%c","HELLO"[1])

As Peter points out, to allow for more than just ASCII:

fmt.Printf("%c", []rune("HELLO")[1])

Can be done via slicing too

package main

import "fmt"

func main() {
    fmt.Print("HELLO"[1:2])
}

NOTE: This solution only works for ASCII characters.

You can also try typecasting it with string.

package main

import "fmt"

func main() {
    fmt.Println(string("Hello"[1]))
}