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Can I use special characters in constant names in PHP?

Hey guys,

I was working on a PHP project recently and came across a doubt regarding constant names. I was wondering if it's possible to use special characters in constant names in PHP.

I know that PHP allows us to define constants using the `define()` function and the constant names are usually in uppercase letters. But what if I want to use special characters like "@", "$", "#", etc. in the constant name? Will it cause any issues or will PHP handle it gracefully?

I couldn't find much information about this specific topic in the PHP documentation, so I thought of posting my question here. Have any of you ever used special characters in constant names? If so, did you face any problems or was it all smooth sailing?

I'm really eager to learn from your experiences and get some insights on this. Thanks in advance for all your help!

All Replies


Hey there,

Yes, I have used special characters in constant names in PHP before. In my experience, it is possible to include special characters like "@" or "$" in constant names without facing any issues. PHP handles them just fine.

However, there are a few things you should keep in mind. Since constant names are case-sensitive, make sure to maintain the exact case when using special characters. For example, if you define a constant as `define('MY_CONSTANT', 'something');`, you need to refer to it as `MY_CONSTANT` throughout your code. If you mistakenly use a different case, the constant won't be recognized.

Additionally, it's important to note that special characters in constant names can make your code harder to read and maintain. It is generally recommended to stick to alphanumeric characters and underscores for constant names. This helps improve code readability and ensures consistency across your project.

So, while you technically can use special characters in constant names, it's best to use them sparingly and only when absolutely necessary. It's good practice to keep constant names simple, descriptive, and free of any special characters unless they are integral to the meaning of the constant.

I hope this helps! Let me know if you have any further questions.


Hey folks,

I've actually had some experience using special characters in constant names while working on a PHP project. In my case, I needed to include the "#" symbol in a constant name to represent a unique identifier for a specific functionality.

Although PHP does allow using special characters in constant names, it's essential to be cautious when doing so. One issue I encountered was when working with external libraries or frameworks that didn't handle special characters well. This resulted in compatibility issues, as those libraries couldn't interpret the constant name correctly and would throw errors.

Moreover, using special characters in constant names can lead to confusion when collaborating with other developers. It may make the code harder to understand and maintain, especially for team members who are not familiar with the codebase or the specific purpose of the constant.

Therefore, based on my experience, I would advise using special characters judiciously when it's absolutely necessary for conveying the intended meaning of the constant. Keeping constant names as simple and alphanumeric as possible is generally a better approach to maintain code readability and compatibility with external dependencies.

Feel free to ask if you have further queries—I'm here to help!

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