程序代码：

 #include <stdio.h>
  #define PT    3.5;
  #define S(x)  PT*（x）*（x）;
  main()
  {
     int a = 1, b = 2;
     printf("%4.1f\n", S(a+b));
  }

程序代码：

#include <stdio.h>
#define PT    3.5
#define S(x)  PT*(x)*(x)
main()
{
    int a = 1, b = 2;
    printf("%4.1f\n", S(a+b));
}