How to use regular expressions to verify the legitimacy of email subject lines in golang

With the popularity of the Internet, email is becoming more and more important in our daily life and work. However, sometimes we receive some illegal email subject lines, which not only disrupts our normal habit of sending and receiving emails, but also brings a lot of trouble to our work and life. Therefore, for developers, how to verify the legitimacy of email subject lines is an important task when writing email-related applications. This article will introduce how to use regular expressions in golang to verify the legitimacy of email subject lines.

First of all, we need to understand the format of the email subject line. The email subject line is composed of 3 parts: name and address part, @ symbol and domain name part. Among them, the name address part can be Chinese, English or numbers. The @ symbol is the separator connecting the name address and domain name parts. The domain name part can be a single domain name or multiple domain names connected by ".". For example, here are some legitimate email subject lines:

• "王小明"749a8bd4d3f86e6244f79d963cad29db
• "Tom"de21333e9565fd666985e1815440dd0f

Next, we can use regular expressions in golang to verify whether the email subject line is legal. In golang, we can use the regexp package to operate regular expressions. The following is a piece of golang code to verify the legitimacy of the email subject line:

package main

import (
    "fmt"
    "regexp"
)

func main() {
    // 邮件主题行正则表达式
    pattern := `^([p{Han}w]+|"[p{Han}ws]+"|w+)s*<(w+([-+.]w+)*@w+([-.]w+)*.w+([-.]w+)*)>$`
    // 邮件主题行数据
    subject1 := "王小明<wangxiaoming@example.com>"
    subject2 := "“Tom”<tom@abc.example.com>"
    subject3 := "tom@abc.example.com"
    // 验证邮件主题行
    match1, _ := regexp.MatchString(pattern, subject1)
    match2, _ := regexp.MatchString(pattern, subject2)
    match3, _ := regexp.MatchString(pattern, subject3)
    // 输出验证结果
    fmt.Println(subject1, "匹配结果：", match1)
    fmt.Println(subject2, "匹配结果：", match2)
    fmt.Println(subject3, "匹配结果：", match3)
}

The above code first defines a regular expression for the email subject line, and then uses the MatchString method to verify whether the email subject line matches the regular expression. It should be noted that we use the Unicode category in golang, namely p{Han} to match Chinese characters. In addition, for the convenience of reading, we write the regular expression into multiple lines. If you want to use it in the code, you need to write it into one line, or use backslashes to separate it into lines.

With the above code, we can verify that the legitimate subject line of the email is verified without any doubt. Of course, the format of the email subject line is far more than this. Developers need to verify all the various formats of the email to ensure the robustness of the program.

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