C++ struct definition [duplicate]

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Possible Duplicate:

What does ‘unsigned temp:3’ means

I just found this code in a book (was used in an example)

typedef struct {
unsigned int A:1;
unsigned int B:1;
unsigned int C:1;
} Stage;

What is the meaning of this structure definition? (the A:1;)

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Those are C bitfields. In compliant compilers, the combination of A B and C do not occupy more than one int. A, B, and C occupy one bit each in the integer.