In a C struct, what does the expression "int i : 5" mean?

Question

In a C struct, what does the expression "int i : 5" mean?

Answer 1

It means i will occupy 5 bits of an int. Which 5 bits, however, depends on what else is in the struct.

For example:

typedef struct {

   int i : 5;

   int j : 3;

   int k : 24;

} BitFields;

sizeof(BitFields) = sizeof(int).

i occupies bits 0 through 4

j is in bits 5 through 7

k in bits 8 through 31

Answer 2

It means i defined as a 5 bits integer.

peng

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