Go: Retrieve a string from between two characters or other strings

Question

Let\'s say for example that I have one string, like this:

Hello World!

What Go code would be able to extract Hel

Answer 1

func findInString(str, start, end string) ([]byte, error) {
    var match []byte
    index := strings.Index(str, start)

    if index == -1 {
        return match, errors.New("Not found")
    }

    index += len(start)

    for {
        char := str[index]

        if strings.HasPrefix(str[index:index+len(match)], end) {
            break
        }

        match = append(match, char)
        index++
    }

    return match, nil
}