package main

import (
	"fmt"
	"strings"
)

func main() {
	str := "aaa bbb ddd fff aaa"
	keyword := "aaa"
	str = strings.ReplaceAll(str, keyword, "**")

	fmt.Println(str)
}

package main

import (
	"fmt"
	"strings"
)

func main() {
	str := "aaa bbb ddd fff aaa"
	keyword := "aaa"
	replacer := strings.NewReplacer(keyword, "**")
	str = replacer.Replace(str)

	fmt.Println(str)
}