Why function is necessary? In your project, sometimes you need to perform same task multiple times. Therefore, you need to write the same code every time it requires. It makes programming time consuming, boring, and tedious. To make development easier, Read more
An array in php is an ordered map that associates values to keys.
If a variable is meant to be contain a value that may change, then, a constant is meant to be contain a value that never change.
Variable is a memorable name of computer memory cell(s) that can hold a value during the execution of the program and the value may change.