Overview

In GO string are UTF-8 encoded. strings package of GO provides an Index method that can be used to get the index of the first occurrence of a substring in a particular string. It returns -1 is the substring is not present in the given string.

Below is the signature of the function

func Index(s, substr string) int 

Let’s look at the working code

Code:

package main
import (
"fmt"
"strings"
)
func main() {
//Output will be 1 as "bc" is present in "abcdef" at index 1
res := strings.Index("abcdef", "bc")
fmt.Println(res)
//Output will be 2 as "cd" is present in "abcdefabcdef" at index 2
res = strings.Index("abcdefabcdef", "cd")
fmt.Println(res)
//Output will be -1 as "ba" is not present in "abcdef"
res = strings.Index("abcdef", "ba")
fmt.Println(res)
}

Output:

1
2
-1