C Functions Question:

Bit Fields allow the packing of data in a structure.

This is especially useful when memory or data storage is at a premium

The maximum length of the field should be less than or equal to the integer word length of the computer.some compilers may allow memory overlap for the fields.Some store the next field in the next word.
C lets us do this in a structure definition by putting :bit length after the variable:
struct pack
{
unsigned int funny_int:9;
}p;

Also, Boolean datatype flags can be stored compactly as a series of bits using the bits fields. Each Boolean flag is stored in a separate bit.