What does this construction means?

Question

class Test 
{

    struct
    {
      unsigned has_some_value1: 1;
      unsigned has_some_value2: 1;
    } info;
};

What does unsigned has_some_value1: 1; means?

Should be the following statement true: sizoef(type) == bit1 + ... + bitn ?

http://stackoverflow.com/questions/1604968/what-does-this-c-code-mean — sve, Nov 22 '13 at 14:16

score 2 · Accepted Answer · answered Nov 22 '13 at 14:26

2

These are called "bit fields". has_some_value1 occupies one bit. has_some_value2 also occupies one bit—maybe the next physical bit in memory, or maybe not (depends how your compiler is configured to handle bit field alignment).

answered Nov 22 '13 at 14:26

jez

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sizeof() will obviously, at a very minimum, round up the size to the next whole number of *bytes* after adding up the bit widths and dividing by 8. But it may also be more, due to architecture- and compiler-specific struct alignment issues. – jez Nov 22 '13 at 14:39

score 1 · Answer 2 · answered Nov 22 '13 at 14:19

1

A bitfield in a nonstatic instance of an un-named struct called "info", which is itself a member of "Test".

answered Nov 22 '13 at 14:19

defube

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What does this construction means?

2 Answers2