Bitfields. Why is there no output?

Question

#include <iostream>
using namespace std;
struct bitfield
{
    unsigned char a : 3, b : 3;
};

int main()
{
    bitfield bf;
    bf.a = 7;
    cout << bf.a;   
    char c;
    cin >> c;
    return 0;
}

I am using VC++ with its latest compiler. When i type cast bf.a to int it gives the desired output (7). But when i dont type cast it, it gives no output and gives no errors. Why is it so?

Answer 1

When i type cast bf.a to int it gives the desired output (7). But when i dont type cast it, it gives no output and gives no errors. Why is it so?

The character (number 7) was written to the console. Character 7 is the bell character.

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So you can't see it, but you can hear it. Or rather I could hear the notification sound on Windows 10 when I ran the program.

The same output is generated with:

cout << '\a';

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The bell is part of a group of characters that can be referenced with escape sequences.

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Note that in this case the use of a char bitfield is not guaranteed by the standard. See here for a question regarding the use of char bitfields.