(PHP4 >= 4.0b4)

is_resource --  Finds whether a variable is a resource


int is_resource (mixed var)

is_resource() returns true if the variable given by the var parameter is a resource, otherwise it returns false.

Resources are things like file or database result handles that are allocated and freed by internal PHP functions and that may need some cleanup when they are no longer in use but haven't been freed by user code.