c - Accessing lower half of a 64bit integer -

How can C or C ++ access to the lower half of a 64 bit integer? I can do it easily in the assembly but how to do it in C / C ++, there is no clue.

Edit: What about reaching the upper half?

Longer Lohrfl = Bigon & amp; 0xFFFFFFFFLL; Longer Upper Half = (BigOn> 32) & amp; 0xFFFFFFFFLL;

Sorry, if hexadecimal liters require some prefix / suffix, then I am not very familiar with C. If you know, please answer it.