用C++计算圆的周长和面积

 1 #include <stdio.h>

 2 void main()

 3 {

 4     float r;

 5     double cir,area;

 6     const double pi=3.1415926;

 7     printf (“please enter a numbers as radius:”);

 8     scanf (“%f”,&r);

 9     cir=2.0*pi*r;

10     area=pi*r*r;

11     printf (“the circumference is: %f\n”,cir);

12     printf (“the area is: %f\n”,area);

13 

14 }