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

Using regular expressions in golang to verify whether the URL address is a fifth-level domain name can be achieved through the following steps:

First, we need to understand what a fifth-level domain name is, which refers to a complete domain name It consists of 5 parts, for example: https://www.example.com.cn. The five parts are: protocol, host name, second-level domain name, third-level domain name and top-level domain name. In this article, we will verify whether a URL address is in the format of a fifth-level domain name.

Next, we need to understand how to use regular expressions in golang. You can use the regexp package in golang to implement regular expression matching. The usage method is as follows:

import "regexp"

func main() {
    match, err := regexp.MatchString("正则表达式", "匹配的字符串")
    if err != nil {
        // 处理错误
    }
    if match {
        // 匹配成功
    } else {
        // 匹配失败
    }
}

Then, we need to write a regular expression to verify whether the URL address is in the format of a fifth-level domain name. The regular expression should contain the following parts:

1. Matching protocol part: it can be http or https.
2. Match the host name part: it can be any valid host name, such as www.example.com.cn.
3. Match the second-level domain name part: it can be any valid second-level domain name, such as abc.example.com.cn.
4. Match the third-level domain name part: It can be any valid third-level domain name, such as xyz.abc.example.com.cn.
5. Match the top-level domain name part: it can be a specified top-level domain name, such as .cn, .com, etc.

To sum up, the following is a regular expression that can verify whether the URL address is a fifth-level domain name:

^(http|https)://([a-z0-9-]+.)+[a-z0-9-]{2,}$ 

Finally, we use the above regular expression to verify the URL Whether the address is in the format of a fifth-level domain name, the code is as follows:

import "regexp"

func isValidURL(url string) bool {
    re := regexp.MustCompile(`^(http|https)://([a-z0-9-]+.)+[a-z0-9-]{2,}$`)
    return re.MatchString(url)
}

func main() {
    url := "https://www.example.com.cn"
    if isValidURL(url) {
        fmt.Println("URL地址是五级域名的格式")
    } else {
        fmt.Println("URL地址不是五级域名的格式")
    }
}

In the above code, we verify whether the URL address is in the format of a fifth-level domain name by calling the isValidURL function. If the URL address is in the format of a fifth-level domain name, the function will return true, otherwise it will return false.

Summary:

This article introduces how to use regular expressions to verify whether the URL address is in the format of a fifth-level domain name in golang. It should be noted that in actual applications, we should write corresponding regular expressions to verify the format of the URL address according to the actual situation.

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