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

With the development of the Internet, there are more and more websites, and the URLs are becoming more and more diverse. However, for important websites such as corporate websites, the choice of domain name is very important. In order to increase the security and stability of the website, some companies choose to use tenth-level domain names. So, how to use regular expressions in golang to verify whether the URL address is a tenth-level domain name? This article explains how.

1. What is a tenth-level domain name?

In the Internet, a domain name is a way to access a website. What we usually call a domain name is a first- and second-level domain name, such as: baidu.com. The tenth-level domain name refers to the addition of eight sub-domain names on the basis of the first- and second-level domain names, for example: www.a.b.c.d.e.f.g.h.i.com.

2. Use regular expressions to verify whether the URL address is a tenth-level domain name

You can use regular expressions to verify whether the URL is a tenth-level domain name. In golang, we can use the "regexp" package to implement regular expression verification. The specific implementation is as follows:

package main

import (
    "fmt"
    "regexp"
)

func verifyURL(url string) bool {
    format := `^(?:[a-z0-9]+.){9}[a-z]{2,4}$`
    match, _ := regexp.MatchString(format, url)
    return match
}

func main() {
    url1 := "www.a.b.c.d.e.f.g.h.i.com"
    url2 := "www.a.b.c.d.e.f.g.h.i.cn"
    url3 := "www.a.b.c.d.e.f.g.h.i.cn/index.html"
    fmt.Println(verifyURL(url1))  // true
    fmt.Println(verifyURL(url2))  // true
    fmt.Println(verifyURL(url3))  // false
}

In the above code, we use the regular expression string "^(?:[a-z0-9] .){9}[a-z]{2,4}$" to Verify whether the URL address is a tenth-level domain name. Among them, "^" represents the beginning of the string, "(?:[a-z0-9] .){9}" represents matching one or more letters or numbers, and a period, thus matching 8 subdomain names , and finally matches a top-level domain name, which is "[a-z]{2,4}". Since this regular expression matches the entire string, adding "(?:" at the beginning indicates that only grouping is performed without matching, and finally adding "$" at the end indicates the end of the string.

3. Notes

When using regular expressions to verify whether the URL address is a tenth-level domain name, you need to pay attention to the following points:

1. You need to exclude the protocol in the URL during verification. For example: http://www.a.b.c.d.e.f.g.h.i.com You need to remove "http://" for verification.
2. Be sure to consider special circumstances, such as the URL containing a path or the "@" symbol, etc. , these situations cannot be regarded as tenth-level domain names.

4. Conclusion

Through the above implementation, we can use regular expressions in golang to very conveniently verify whether the URL address is Tenth-level domain name. Of course, for different types of URL addresses, we can also use different regular expressions for verification. Regular expressions are a powerful tool, very useful when implementing string verification, and are also very convenient to use in golang .

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