strstr in go

strstr.go

package main

import (
	"fmt"
	"strings"
)

func main() {
	fmt.Println(strstr("Hello how how are you", "How"))
}

func strstr(haystack string, needle string) []int {
	if len(haystack) <= 0 {
		return []int{0}
	}
	var positions = make([]int, 0)
	var (
		i     int
		j     int
		index int
	)
	var needleLength = len(needle)
	for i = 0; i < len(haystack); i++ {
		index = i
		j = 0

		for strings.ToLower(string(haystack[index])) == strings.ToLower(string(needle[j])) {
			if j == needleLength-1 {
				positions = append(positions, i)
				j = 0
			}
			index++
			j++
		}
	}
	return positions
}