字节

bit/位   取值0...1
byte(字节)=11111111(2)=255(10)=FF(16)
WORD(单字)=2Byte=0...65535   =FFFF
DWORD(双字)=2WORD=4Byte=0...4292967295=FFFFFFFF
int(4字节)，long(4字节),float(4字节),double(8字节)