c 语言 输入三边求三角形的面积和周长?

#include
#include
public void main()
{
double a,b,c;
scanf("%lf%lf%lf",&a,&b,&c);
double area,preimeter;
preimeter=a+b+c;
double p=preimeter/2;
area=sqrt(p*(p-a)*(p-b)*(p-c));
printf("area = %.2lf, preimeter = %.2lf\n",area,preimeter);
getchar(); getchar();
}