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Bit-fields can be used to allow flags or other integer values with small ranges to be packed together to save storage space. When used in structure members, bit fields can improve storage efficiency. Compilers typically allocate consecutive bit-field structure members to the same int-sized storage, as long as they fit into that completely into that storage unit. However, the order of allocation within a storage unit is implementation-defined. Some implementations are "right-to-left": the first member occupies the low-order position of the storage unit. Others are "left-to-right": the first member occupies the high-order position of the storage unit. Calculations that depend on the order bits within a storage unit may produce different results on different implementations.
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