How to use PHP regular expression to validate form data? (detailed steps)

The previous article introduced to you "How to use regular replacement to clear all HTML tags in a string?》, this article continues to introduce to you how to use PHP regular expressions to verify form data?

#How to use PHP regular expressions to validate form data?

First, we lay out our HTML form, and then add the form tag (note: all user-related content must be transmitted using post), and then, we Add the account number, password and email address to the form, and finally add a login button.

Take the code demonstration as an example:

      
  
 账号: 
 密码: 
 邮箱: 
  

The code results are as follows;

The operation result is successful, but the case we gave shows that the account number needs to be composed of letters, numbers and underscores. The password needs to be composed of 8-16 characters of uppercase and lowercase letters and numbers. The email address needs to enter the correct email address. Therefore, we add rules that need to be added by default in the code. The code demonstration is as follows;

      
  
 账号: 
 密码: 
 邮箱: 
  

The code results are as follows As shown;

According to the code display, the content we need is also displayed in the running results, but after we get the default display, we need to define the verification rules. Verification Whether the content output by the user meets the requirements; for example, we take the user as an example, first define $userpattern = '/^\w $/S'; and then make a judgment and add an if conditional sentence. In the if statement, if it is not set The user will not be able to judge the conditional sentence, or will not enter if the setting is wrong, and so on. Let’s take the code as an example:

正确'; }else{ $userInfo = '字母数字以及下划线组成'; } $pwdPattern ='/^[a-zA-Z0-9]{6,13}$/S'; if(isset($_POST['pwd'])){ if(preg_match($pwdPattern,$_POST['pwd'])){ $pwdInfo ='正确'; }else{ $pwdInfo = '6-13位大小写字母以及数字'; } } $emailPattern = '/^\w+@[0-9a-zA-Z]+(\.[a-zA-Z]{2,5})+$/S'; if(isset($_POST['email'])){ if (preg_match( $emailPattern,$_POST['email'])){ $emailInfo = '正确' ; }else{ $emailInfo = '输入正确的email地址'; } } ?>

The code results are as follows;

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