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

Using regular expressions to verify the legitimacy of email addresses in golang is a common requirement. This article will introduce how to use the regular expression library in golang to implement this function.

How to verify the legitimacy of the email address?

Before introducing how to use regular expressions to verify the legitimacy of email addresses in golang, we need to understand the rules for verifying email addresses. An email address usually contains three parts: username, @ symbol and domain name. The username and domain name have their own rules.

• Username rules: The username consists of letters, numbers, underscores and periods. It can have multiple periods, but it cannot start or end with a period, and two periods cannot appear in a row. .
• Domain name rules: A domain name consists of letters, numbers and periods. It can have multiple periods, but it cannot start or end with a period, and two periods cannot appear in a row. The last part of the domain name must be a second- or third-level domain name. The suffix of the second-level domain name is usually .com, .net, .org, etc., and the suffix of the third-level domain name is usually .cn, .edu, .gov, etc.

Through the above rules, we can summarize the regular expression for verifying email addresses, namely:

^[a-zA-Z0-9_] (. )@ [a-zA-Z0-9] (. ).{2,3}$

The meaning of this regular expression is as follows:

• ^ represents the beginning of the string .
• [a-zA-Z0-9_] means at least one letter, number, or underscore.
• (. )* means there can be multiple periods followed by letters, numbers or underscores.
• @ represents the @ symbol.
• [a-zA-Z0-9] means at least one letter or number.
• (. )* means there can be multiple periods followed by letters or numbers.
• [.] represents a period.
• [a-zA-Z]{2,3} means the last part must be two or three letters.

How to use regular expressions to verify the legitimacy of email addresses in golang?

Golang has a built-in regexp package, which can easily use regular expressions. The following is the implementation code for using the regexp package to verify the email address:

package main

import (
    "fmt"
    "regexp"
)

func IsEmailValid(email string) bool {
    emailRegex := "^[a-zA-Z0-9_]+([.][a-zA-Z0-9_]+)*@[a-zA-Z0-9]+([.][a-zA-Z0-9]+)*[.][a-zA-Z]{2,3}$"
    match, err := regexp.MatchString(emailRegex, email)
    if err != nil {
        fmt.Println(err)
        return false
    }
    return match
}

func main() {
    email := "test@gmail.com"
    if IsEmailValid(email) {
        fmt.Println("Valid email address: ", email)
    } else {
        fmt.Println("Invalid email address: ", email)
    }
}

In the above code, we define a IsEmailValid function to verify the legitimacy of the email address. In this function, We use the regexp.MatchString function to determine whether a given email address matches a regular expression.

It should be noted that the regexp.MatchString function will automatically add ^ and $ symbols before and after the regular expression when matching. , so there is no need to add these two symbols in the regular expression.

If the given email address matches the regular expression, return true, otherwise return false.

Summary

This article introduces how to use the regular expression library in golang to verify the legitimacy of email addresses. It should be noted that regular expressions are just a tool. We need to use different regular expressions to solve different problems. In actual use, we also need to consider issues such as performance and security.

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