how to output binary numbers by "cout"?

[ImLazy]

I use this code, but failed.

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#include <iostream>
#include <iomanip>

using namespace std;

int main() {
    int a = 1234;
    cout << setbase(2) << a << endl;
    return 0;
}

The output is still "1234".
Help.

[Krzysztof Duleba]

http://www.dinkumware.com/manuals/reade ... ml#setbase

As you see, setbase supports only bases of 8, 10 and 16.

I'm not aware of any standard way of displaying binary numbers.

[Moha]

Yes, there is no way to output binary numbers directly with cout.

[ImLazy]

Oh, I see.
Thanks.

Another question. This code:

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#include <iostream>
#include <iomanip>

using namespace std;

int main() {
    int a = 1234;
    cout.setf(ios::hex);
    cout << a << endl;
    cout << hex << a << endl;
    return 0;
}

why the output is

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1234
4d2

[Krzysztof Duleba]

Calling cout.setf(ios::hex) sets the flag, but it doesn't unset the others. The result is that both ios::hex and ios::dec are set.

There is another flavour of setf method, it takes two arguments and replaces selected bits (first argument) under a mask (second argument). Example:

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cout.setf(ios::hex, ios::basefield);

This is equivalent to

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cout.flags((cout.flags() & ~ios::basefield) | (ios::hex & ios::basefield))

In fact (ios::hex & ios::basefield) is equal to ios::hex, I just wanted to give the general formula.

[ImLazy]

Oh, I see. Thank you for your help and also for your telling me a good website.