First of all, ULONGLONG is capitalized, indicating that it is a macro definition type of typedef or define, and you can find its original definition in other parts of the program. \x0d\ \x0d\ Literally, u is unsigned, long is two long, that is to say, it is an unsigned double-length；; \x0d\ is probably 1.64 bit unsigned length shaping; (It doesn't seem to exist in this C language) \x0d\ conjecture 2. Unsigned double precision type; (This is a long double type in C language) \x0d\ x0d \ Second, the above is just speculation: \ x0d \ The final answer must be obtained from the place defined by the program!