PHP Constants Example

Constant PI: 3.14159

Constant GREETING: Hello, World!

Calculate Circle Area: PI * 5 * 5 = 78.53975

Welcome Message: Hello, World!

In PHP, constants are similar to variables, but they differ in several key ways:

• Constants are defined using the define() function and cannot be changed once defined.
• Variables, on the other hand, can have their values changed at any time during the script.
• Constants are accessible without the need of a dollar sign. ($), Variables, on the other hand, are accessible with a dollar symbol.
• Constants are typically used for values that should not change, such as mathematical constants or configuration settings.

In this script, for example, we set constants for the value of pi (code>PI/code>) and a greeting message (code>GREETING/code>), which we subsequently utilized in calculations and output.