# IP 地址无效化
---

给你一个有效的 IPv4 地址 address，返回这个 IP 地址的无效化版本。

所谓无效化 IP 地址，其实就是用 "[.]" 代替了每个 "."。

 
示例 1：

输入：address = "1.1.1.1"
输出："1[.]1[.]1[.]1"

示例 2：

输入：address = "255.100.50.0"
输出："255[.]100[.]50[.]0"

:::success

package main

import (
	"fmt"
	"regexp"
	"strings"
)

func main() {
	fmt.Println("strings Replace", defangIPaddr("192.168.1.1"))
	fmt.Println("strings ReplaceAll", defangIPaddr1("192.168.1.1"))
	fmt.Println("strings Join + Split", defangIPaddr2("192.168.1.1"))
	fmt.Println("string to []byte, []byte to string a", defangIPaddr3("192.168.1.1"))
	fmt.Println("string to []byte, []byte to string b", defangIPaddr4("192.168.1.1"))
	fmt.Println("string to []string, strings Join []string", defangIPaddr5("192.168.1.1"))
	fmt.Println("regexp", defangIPaddr6("192.168.1.1"))
}

// strings ReplaceAll
func defangIPaddr(address string) string {
    return strings.Replace(address, ".", "[.]", -1) // -1表示替换时没有数量限制
}

// strings ReplaceAll
func defangIPaddr1(address string) string {
    return strings.ReplaceAll(address, ".", "[.]") // 不重叠实例的旧替换为新
}

// strings Join+Split
func defangIPaddr2(address string) string {
    return strings.Join(strings.Split(address, "."), "[.]") // Join 连接字符串， Split拆分字符串
}

// string to []byte, []byte to string
func defangIPaddr3(address string) string {
	bytes := make([]byte, 0)

	for i := 0; i < len(address); i++ {
		if address[i] != '.' {
			bytes = append(bytes, address[i])
		} else {
			bytes = append(bytes, '[', '.', ']')
		}
	}

	return string(bytes)
}

func defangIPaddr4(address string) string {
	bytes := make([]byte, 0)

	for _, value := range address {
		if value != '.' {
			bytes = append(bytes, byte(value))
		} else {
			bytes = append(bytes, '[', '.', ']')
		}
	}

	return string(bytes)
}

// string to []string, strings Join []string
func defangIPaddr5(address string) string {
	result := make([]string, 0)

	for _, value := range address {
		if value == '.' {
			result = append(result, "[.]")
		} else {
			result = append(result, string(value))
		}
	}
	return strings.Join(result, "")
}

func defangIPaddr6(address string) string {
	return regexp.MustCompile("(\\d+)\\.(\\d+)\\.(\\d+)\\.(\\d+)").ReplaceAllString(address, "$1[.]$2[.]$3[.]$4")
}

:::

- **结果输出**

strings Replace 192[.]168[.]1[.]1
strings ReplaceAll 192[.]168[.]1[.]1
strings Join + Split 192[.]168[.]1[.]1
string to []byte, []byte to string a 192[.]168[.]1[.]1
string to []byte, []byte to string b 192[.]168[.]1[.]1
string to []string, strings Join []string 192[.]168[.]1[.]1
regexp 192[.]168[.]1[.]1

###### tags: `LeeCode`