%g doesn't print as many decimal places as %f

Take a look at this:

Code:

int main() {
	double x, y;
	x = 5;
	y = 2.75;

	printf("x is %f and y is %f\n", x, y);

	return(0);
}

That will print 'x is 5.00000000 and y is 2.7500000000000' or somesuch.
I wanted to get rid of the useless zeroes, so somebody suggested using %g instead. Problem is, that rounds to the nearest ten thousanth (four decimal places), while %f works to six (nearest millionth).

Any ideas? If possible, I'd like to retain the functionality of %g but have six significant decimal places.

%g only truncates closing zeroes; at least on my machine, this code

Code:

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main(void) {

    float b = 0.0078125f;
    printf("%f %g %6g\n", b, b, b);
    return 0;
}

prints this

Code:

0.007813 0.0078125 0.0078125

But you should be able to specify a print format with %g just as well as with %f.