How to use regular expressions in golang to verify whether the URL address is a first-level domain name

In golang, it is very simple to use regular expressions to verify first-level domain names. First, we need to understand what a first-level domain name is.

The first-level domain name refers to the highest-level domain name among Internet domain names, usually consisting of one word or abbreviation. For example, com in google.com is the first-level domain name. Therefore, the URL address we want to verify should be in a format similar to www.google.com or abc.baidu.com.

Next, we can use golang's regular expression library regexp for verification. The following is a sample code:

package main

import (
    "fmt"
    "regexp"
)

func main() {
    re := regexp.MustCompile(`^[a-zA-Z0-9]+(.[a-zA-Z0-9]+)*.[a-zA-Z]{2,}$`)

    urls := []string{"www.google.com", "abc.baidu.com", "www.google.cn", "abc.baidu.cn", "www.123.com", "www.google", "www.google."}

    for _, url := range urls {
        if re.MatchString(url) {
            fmt.Println(url, "是一级域名")
        } else {
            fmt.Println(url, "不是一级域名")
        }
    }
}

In the above code, we first define a regular expression re, which can match URL addresses that conform to the first-level domain name format. Then, we defined a string slice urls for testing, which contains some URL addresses that conform to the first-level domain name format and some URL addresses that do not conform to the format. Finally, we use a for loop to traverse each URL address in the slice and use the re.MatchString function to verify whether it is a first-level domain name.

The output result of this code is:

www.google.com 是一级域名
abc.baidu.com 是一级域名
www.google.cn 是一级域名
abc.baidu.cn 是一级域名
www.123.com 是一级域名
www.google 不是一级域名
www.google. 不是一级域名

It can be seen from the output result that the URL addresses that conform to the first-level domain name format are successfully verified, but do not conform to the first-level domain name format. URL addresses are excluded.

In summary, it is very simple to use the regular expression library regexp in golang to verify whether the URL address is a first-level domain name. Just define a suitable regular expression and then use the re.MatchString function to verify it. Hope this article can be helpful to everyone!

The above is the detailed content of How to use regular expressions in golang to verify whether the URL address is a first-level domain name. For more information, please follow other related articles on the PHP Chinese website!