uses of type conversion?

[vw4x4]

1) what are the uses of type conversion?
2)what are the uses of forcing data types to be stored as another data type?
3) 0x8000=32768. 0x8000 is stored as unsigned int.but 32768 is stored as a signed int.why?

[helios]

3. Because hex notation is typically used with bitwise operations. Bitwise operations behave unintuitively with signed operands. On the other hand, if you do 1000-1001, you expect to get -1, not 2ⁿ-1.