PHP define vs const: Key Differences

In PHP, both define and const are used to define constants, but they have some differences.

1. Define is a function, while const is a language structure. This means that define is executed at runtime, while const is executed at compile time.
2. You can define constants anywhere, including inside functions and loops, while const can only be used in classes.
3. When defining constants, expressions can be used with ‘define’, while ‘const’ can only use scalar values (such as integers, strings, or boolean values).
4. Constants defined with const are static and cannot be assigned through variables or expressions, while constants defined with define are dynamic and can be assigned as needed.

In general, if you need to define constants within a class, you should use const. Otherwise, if you need to define constants in a global scope, you can use define.