For most architectures, there is no signed–unsigned type distinction in the
machine language. Nevertheless,
arithmetic instructions usually set different
CPU flags such as the
carry flag for unsigned arithmetic and the
overflow flag for signed. Those values can be taken into account by subsequent
branch or arithmetic commands. The
C programming language, along with its derivatives (except
Java which lacks unsigned types), implements a signedness for all
integer data types, as well as for
"character". For Integers, the modifier defines the type to be unsigned. The default integer signedness outside bit-fields is signed, but can be set explicitly with modifier. By contrast, the C standard declares , , and , to be
three distinct types, but specifies that all three must have the same size and alignment. Further, must have the same numeric range as either or , but the choice of which depends on the platform. Integer
literals can be made unsigned with suffix. Compilers often issue a warning when comparisons are made between signed and unsigned numbers or when one is
cast to the other. These are potentially dangerous operations as the ranges of the signed and unsigned types are different. ==See also==