I am transitioning from Java to C++ and have some questions about the `long` data type. In Java, to hold an integer greater than 232, you would simply write `long x;`. However, in C++, it seems that `long` is both a data type and a modifier. There seems to be several ways to use `long`: ``` long x; long long x; long int x; long long int x; ``` Also, it seems there are things such as: ``` long double x; ``` and so on. What is the difference between all of these various data types, and do they all have the same purpose?