Скачать или смотреть How to Validate Usernames with Allowed Characters in PHP

Discover how to efficiently validate usernames in PHP, ensuring they only contain allowed alpha-numeric characters and specific symbols without overcomplicating your code.
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This video is based on the question https://stackoverflow.com/q/74200659/ asked by the user 'willyrire' ( https://stackoverflow.com/u/20152510/ ) and on the answer https://stackoverflow.com/a/74200704/ provided by the user 'cgrom' ( https://stackoverflow.com/u/12376447/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Introduction

When developing applications that require user registration, validating usernames is crucial. Ensuring that a username consists solely of specific alphanumeric characters, along with particular characters or symbols, can prevent various issues, including security concerns and usability problems. If you've ever wondered how to validate a username against a complex character set in PHP without making your code too cumbersome, you’re in the right place.

The Problem

You want to ensure that a username contains only designated characters, in this case:

Uppercase letters: A-Z

Lowercase letters: a-z

Digits: 0-9

Special characters: ._ and spaces

The Challenge: While regular expressions (preg_match) are an option, you’re looking for a more straightforward solution that avoids the complexity of managing numerous characters.

The Solution

In this guide, we will use a simple PHP function that iterates through each character of the username to check if it belongs to our set of allowed characters. Let’s break it down step by step.

Step 1: Define the Function

First, we’ll create a PHP function named validateUsername. This function will accept the username, as well as specify minimum and maximum lengths:

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

Step 2: Testing the Function

Next, let's create an array of usernames to check if our function works correctly. Here’s how you can write a simple test:

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

Overview of the Code Functionality

Character Set: The $allowed_chars string lists all characters that are permitted in the username.

Length Check: Before validating characters, the function checks if the username falls within the specified length.

Character Validation: It iterates through each character of the username using a for loop and checks whether it's in the list of allowed characters.

Conclusion

Using this simplified validation approach eliminates the need for idealizing complex regular expressions. Instead, by breaking down your requirements into manageable segments, you can ensure that usernames are validated effectively.

With the validateUsername function, you now have a robust solution for checking usernames against a custom set of characters. This can be adapted for various applications that require user input.

Happy coding!