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Learn how to create a comprehensive regex validation for IP address inputs that allows both complete and partial entries in PHP.
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How to Validate Incomplete IP Address Inputs with Regex in PHP

When it comes to web forms, validating user inputs is crucial for maintaining data integrity. One of the common challenges developers face is ensuring that IP addresses entered in a form are compliant with specific formats. In this guide, we will explore how to validate IP addresses that may either be complete or partially entered using regular expressions (regex) in PHP.

Understanding the Problem

You have a form designed to accept IP addresses, and you're required to fulfill three validation conditions:

The user enters a complete IP address, such as 100.10.10.100.

The user includes the first two segments of the IP and uses a star (*) for the remaining parts, like 100.10.*.*.

The user inputs the first three parts and substitutes the last segment with a star (*), resulting in an entry like 100.10.10.*.

Your current regex validation has successfully addressed the complete IP structure. However, it's time to build out functionality to handle the partial entries effectively.

Setting Up the Validation Regex

To meet all three conditions of your IP address validation, you will need to establish different regex patterns that account for the required formats. Let’s break down the regex for each condition.

1. Complete IP Address Validation

This is straightforward and has already been handled in your original validation:

[[See Video to Reveal this Text or Code Snippet]]

2. Two Segments with Wildcards

To allow users to enter the first two segments and replace the last two segments with *, you can use the following regex pattern:

[[See Video to Reveal this Text or Code Snippet]]

Here, \d{1,3} captures 1 to 3 digits for the first two segments, while [*] allows for a wildcard character in the last two segments.

3. Three Segments with a Wildcard

For IP addresses where the first three segments are specified, and the last segment is a wildcard, use the regex below:

[[See Video to Reveal this Text or Code Snippet]]

This pattern connects the complete first three segments with [*] as the placeholder for the last segment.

Implementing the Validation Logic

Now that we have our regex patterns set up, let’s incorporate them into your PHP validation logic:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

With these regex patterns, validating the various forms of IP addresses becomes a seamless process in your PHP application. You can confidently accept complete and partial IP addresses, ensuring your data storage remains accurate and reliable.

By implementing these solutions, you can enhance your form’s usability while keeping data integrity intact.

Feel free to adapt the patterns further based on your specific requirements, and happy coding!