Tt should be a pointer. For example, tt points to data a[ 1] and data type char. Then, after the expression tt++ ends, tt points to a[2], that is, the pointer moves backward by one byte; Of course, if the data type of a[ 1] is int, tt will point to a[2] after tt++, and the pointer will be 4 bytes backward. When (*tt)++ ends, it is equivalent to a[ 1]++, that is, the value in a[ 1] is added to 1. But after the completion of *tt++, as the first floor said, nothing has changed.

The pointer is actually a numerical value, which is the value of the address pointed by the pointer.