Basic PHP development tutorial: Tips for writing regular rules

1. Tips for writing regular rules

Tips for regular rules: write a little and test a little.

Because we need constant regularization and use preg_match to compare whether the match can be successful. If it succeeds, let’s write the next point. Until you finish writing and all matches are successful!

For example, I want to write a regular expression for an email address. The first thing I want to do is list all the commonly used email formats. For example:

liwenkai@phpxy.com liwenkai@corp.baidu.cm liwenkai@126.com l_w_k@xxx.com 12345@qq.com

The commonly used formats mainly include the following. Then we can analyze:

1. First match the character before @ \w+ (because it is 0-9A-Za-z_)

2 . The second one is followed by an @ symbol

3. The third one is written [a-zA-Z0-9-]+ because the main domain names of qq and 126 cannot have underscores. ’s

4. corp.baidu. Or 126. Usually the email suffix is ​​like this. So we can write it as: ([a-zA-Z0-9-]+.){1,2}

##5. The above is to escape . so that it is itself the meaning of. The brackets must be repeated at least once and at most twice.

6. Just follow com|cn|org|gov.cn|net|edu.cn and so on

Therefore, our regular Expression usage:

/\w+@([a-zA-Z0-9-]+.){1,2}(com|cn|org|gov.cn|net|edu.cn) /

The regular expression of the mailbox is successful.

2. Commonly used regular functions

Our commonly used regular functions are:

Please use the manual for these functions. If you have any questions or encounter problems, you can come to our official website to ask questions.

Regular expressions about frequently encountered questions in interviews

3. Several regular expressions that are often tested in interviews are

1. Match email

2. Match mobile phone number

3. Match a URL

4. Use regular expression to match a certain format and take out a certain example

5. Write a collector

Others....

Commonly used regular expressions

The following is a method for quickly searching regular expressions. You must know the details. mean.

Just search and copy if needed!