请教问题。。。。这个问题,求解释
#include <stdio.h>
#include <math.h>
void main ()
{
double a, b, c, s, area;
scanf ("%lf %lf %lf", &a, &b, &c);
s = 1.0/2 * (a+b+c);
area = sqrt(s*(s-a)*(s-b)*(s-c));
printf ("a = %g, b = %g, c = %g, s = %g\n", a, b, c, s);
printf ("area = %f\n", area);
}
其中的%7.2g,我不怎么明白。。。。。为什么要加7.2?