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Are built-in constants reserved keywords in PHP?

Hi everyone,
I'm relatively new to PHP and I have a question regarding built-in constants. Are these constants considered reserved keywords in PHP? I've been reading about constants and their usage in PHP, but I couldn't find a clear answer to this question. I know that PHP has a set of reserved keywords that can't be used as variable names, but I'm not sure if the same applies to built-in constants. Can someone please clarify this for me? Thanks in advance for your help!

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In my experience, built-in constants in PHP are not considered reserved keywords. They are predefined values provided by PHP itself, which can be accessed and used throughout our code. These constants are quite handy, especially when we want to ensure that a certain value remains unchanged throughout our program.

Since they are not reserved keywords, we are free to use them as variable names without any issues. However, it is generally good practice to use variable names that clearly indicate their purpose, rather than reusing built-in constant names. This helps in improving the readability and maintainability of our code.

Overall, PHP's built-in constants are a useful feature that can make our coding experience more efficient.


From my personal experience, I can confirm that built-in constants in PHP are not considered reserved keywords. These constants have provided me with a convenient way to work with predefined values in my code.

Unlike reserved keywords, which have specific meanings and functionalities determined by the PHP language itself, built-in constants are simply preassigned values that can be accessed and utilized in our scripts. They are not exclusive or restricted in any way.

To avoid confusion and maintain clarity in my code, I generally choose not to use built-in constant names as variable names. It's always a good practice to select descriptive and meaningful names for our variables, as it helps in understanding the code and reduces the chances of errors.

In conclusion, PHP's built-in constants have proven to be beneficial tools in my development journey. They have enhanced the readability and efficiency of my code, without any conflicts as they are not treated as reserved keywords in PHP.


Having worked with PHP for quite some time, I can confidently say that built-in constants are not reserved keywords. These constants come in handy when we need to use predefined values repeatedly in our code.

Unlike reserved keywords, which have specific purposes and functionalities defined by PHP, built-in constants are simply predefined values that PHP provides. They can be accessed and utilized without any issues.

In my experience, it's a good practice to use descriptive variable names rather than reusing built-in constant names. This makes our code more readable and helps us avoid any potential conflicts or confusion.

Overall, PHP's built-in constants have been a valuable feature for me. They simplify coding by allowing us to utilize predefined values, and they do not pose any restrictions as reserved keywords do.

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