Sometimes, there are chances that if you make a bit of changes in your source code, it performs faster by a fraction of a second. This does not seem always logical for small projects to spend time in optimization. But when several users load your website at once, micro-optimization can contribute to the speed.
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Database of PHP Defined Constants
How many inbuilt constants are there in PHP? Several? Near to thousand? This experiment is to build a MySQL Database of PHP Constants.