Integer variables can only store integer data, and variable types that cannot be typed have different storage value ranges. The storage types of integer variables mainly include short integer, basic integer int, long integer and so on. Real variables can store a wide range of data, as the name implies, real numbers. Of course, integers are also real numbers and can also be stored. The storage types of real variables mainly include: single precision floating point, double precision floating point double and so on. Char is a character type that stores ASCII codes and can also be used to store integers from 0 to 255. These are long-term, others are available, but they are hardly used.