A recursive function is a function that calls itself, in order to solve a problem. This type of function is often used in situations where a problem can be broken down into smaller, similar yet smaller problems. The function keeps calling itself with modified arguments until a base case is reached, at which point the function stops calling itself and starts returning values. So, do we know all the recursive functions in PHP?
How to Clean After Oneself in PHP : use register_shutdown_function, __destruct and try-finally to make sure the cleaning always happen
All PHP native classes, ranked by usage frequency. Good base to make sure that one know the commonly used PHP classes.