Does std::locale::global make affect to printf() function?

I'm using Russian locale settings on my PC.
If I would set:

class numpunct_withpoint: public numpunct<char>
{
protected:
    /// Override the function that gives the decimal separator.
    char do_decimal_point() const
    {
        return '.';
    }
};
...
locale loc(std::locale::classic(), new numpunct_withpoint);
std::locale::global(loc);

and than

printf("%f", 3.14);

Output is:

3,14

Decimal separator is "," not like in do_decimal_point function! How can I change C locale settings for decimal separator with C++ locale?

Thanks for answer!
But, does C setlocale function make affect to C++ cout object?

setlocale(LC_NUMERIC, "C");

Would this make affect when printing decimal value via cout?