How to verify multiple email addresses using PHP regular expressions

PHP is a very popular programming language that can be used in various fields such as web development, database programming, image processing, etc. In web development, email address verification is a very important task. This article will introduce how to use PHP regular expressions to verify multiple email addresses.

1. Regular expression basics

Regular expression is a tool used to match strings. It can match specific patterns in text. Regular expressions in PHP use the preg_match function for matching. The syntax is as follows:

preg_match(pattern, string, matches, flags, offset)

Among them, pattern is the regular expression pattern; string is The matched string; matches is an array used to store matching results; flags is an optional parameter used to set the matching mode; offset is an optional parameter used to set the position to start the search.

2. Email address format verification

When verifying the email address, we need to first determine the correct email address format. Generally speaking, a valid email address should contain a username and a domain name. Among them, the username can be composed of letters, numbers, underscores, periods and hyphens, and the domain name can be an IP address or a domain name.

According to the above rules, we can write a regular expression to verify the format of the email address. The specific code is as follows:

$pattern = '/^[a-z0-9._% -] @[a-z0-9.-] .[a-z]{2,}$/i';

This regular expression uses some special symbols. Here are some explanations:

• ^ means matching the beginning of the string
• $ means matching the beginning of the string Ending
• [] means matching a group of characters
• • means matching the previous element one or more times
• . means matching The period character
• {2,} means matching the previous element appearing at least 2 times
• i means it is not case sensitive

3. Multiple email addresses Verification

If you need to verify multiple email addresses, we can put them into an array or string, and then use the preg_match_all function to match. The specific code is as follows:

$emails = array('foo@example.com', 'bar@example.com', 'baz@example.com');
$pattern = '/^[ a-z0-9._% -] @[a-z0-9.-] .[a-z]{2,}$/i';
$results = preg_match_all($pattern, implode(',', $emails));

This code uses the implode function to connect multiple email addresses with commas, and then uses the preg_match_all function to match, and the final result is stored in the $results variable.

4. Conclusion

PHP regular expression is a very powerful tool that can be used to validate many types of data. In this article, we introduce how to use PHP regular expressions to verify multiple email addresses. We hope it will be helpful to readers.

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