如何在Go中替换字符串中特定索引处的字母？

Question

I want to replace a letter at a specific index in a string: aaaaaaa -> aaabaaa. Is there a built in way to do this? I wrote the following helper function to use in the mean time:

func main() {
    input := "aaaaaaa"
    output := replaceAtIndex(input, 'b', 3)
}

func replaceAtIndex(input string, replacement byte, index int) string {
    return strings.Join([]string{input[:index], string(replacement), input[index+1:]}, "")
}

Answer 1

You can concatenate strings with the + operator :

return input[:index] + string(replacement) + input[index+1:]

Be careful that index isn't the index of a "letter" but of the byte.