The length of the string "Hello, World!" is 13.
Hello, John!
Functions in PHP are blocks of reusable code that perform a specific task. They allow you to organize code, make it more readable, and avoid repetition.
A built-in function is a function that is provided by PHP and is available for use without any additional setup. Examples include strlen() which returns the length of a string.
User-defined functions are functions that you create yourself. They are defined using the function keyword followed by the function name, parameters, and code block. You can then call the function by its name and pass arguments to it.
Functions can have parameters which are variables that you can pass to the function when you call it. These parameters allow functions to be more flexible and reusable.
Functions can also return values using the return statement. This allows functions to perform computations or operations and then return a result back to the caller.