The Go Cookbook

Accessing Substrings

How do I access parts of a given string?

Go allows you to access parts of a string via the normal indexing primitives you’re accustomed to using with arrays and slices. In particular, it allows you to access mystring[n:m]. Either n or m can be omitted, which implies from the beginning or to the end, respectively. There’s also the primitive len(s), which gives you the number of characters in the string.

Here are some examples:

package main

import "fmt"

func main() {
	s := "Hello World"
	fmt.Println(s[:5])           // the first 5 characters
	fmt.Println(s[:len(s)-6])    // the same, but counting back from the end
	fmt.Println(s[1:])           // all except the first character
	fmt.Println(s[len(s)-5:])    // the last 5 characters
	fmt.Println(s[1 : len(s)-1]) // all except the first and last
}

$ go run test_index.go
Hello
Hello
ello World
World
ello Worl

Accessing strings by character, word or token are covered in the Processing a String One Word or Character at a Time recipe.