String 替换golang中出现的第n个字符串

如何替换golang中字符串的第n次出现（在本例中为第二次出现）？下面的代码将示例字符串

optimism from optimism

替换为

o from optimism

，我希望它是

optimism from

package main

import (
    "fmt"
    "strings"
)

func main() {
    mystring := "optimismo from optimism"
    excludingSecond := strings.Replace(mystring, "optimism", "", 1)
    fmt.Println(excludingSecond)
}

---

如果你总是知道会有两个索引，你可以先找到第一个的索引，然后对之后的所有内容进行替换，最后将它们组合在一起

比如说,

package main

import (
    "fmt"
    "strings"
)

// Replace the nth occurrence of old in s by new.
func replaceNth(s, old, new string, n int) string {
    i := 0
    for m := 1; m <= n; m++ {
        x := strings.Index(s[i:], old)
        if x < 0 {
            break
        }
        i += x
        if m == n {
            return s[:i] + new + s[i+len(old):]
        }
        i += len(old)
    }
    return s
}

func main() {
    s := "optimismo from optimism"
    fmt.Printf("%q\n", s)
    t := replaceNth(s, "optimism", "", 2)
    fmt.Printf("%q\n", t)
}

---

对于任何在这篇文章上绊倒并希望取代最后一次出现的人

package main

import (
    "fmt"
    "strings"
)

func main() {
    mystring := "optimismo from optimism"

    i := strings.LastIndex(mystring, "optimism")
    excludingLast := mystring[:i] + strings.Replace(mystring[i:], "optimism", "", 1)
    fmt.Println(excludingLast)
}

---

你总是知道会有两个吗？

"optimismo from optimism"
"optimismo from "

package main

import (
    "fmt"
    "strings"
)

func main() {
    mystring := "optimismo from optimism"

    i := strings.LastIndex(mystring, "optimism")
    excludingLast := mystring[:i] + strings.Replace(mystring[i:], "optimism", "", 1)
    fmt.Println(excludingLast)
}