编辑代码

#include <stdio.h>
#define S(a,b) a*b
int main () {
    //area of rectangle 
    float a;
    float b;
    float Area;

    printf("input a:");
    scanf("%f",&a);
    printf("input b:");
    scanf("%f",&b);
    Area = S(a,b);

    printf("%10.4f",Area);
    return 0;
}