C程序习题-使用宏求三角形面积[9.3]

#include <stdio.h>
#include <math.h>
#define S(A,B,C) (((A) + (B) + (C)) / 2 )
#define AREA(A,B,C) sqrt(S(A,B,C) * (S(A,B,C) - A) * (S(A,B,C) - B) * (S(A,B,C) - C))

int main(int argc, char *argv[])
{
    int a,b,c;
    float area;
    printf("please input a,b,c:");
    scanf("%d,%d,%d",&a,&b,&c);
    area = AREA(a,b,c);
    if (a + b > c && a + c > b && b + c > a)
    {
       printf("the area is : %.2f",area);
    }
    else
    {
        printf("is not a triangle!");
    }
    system("pause");
    return 0;
}