#difine pai 3.14159

main()

{

float radius=0.0;

float circle=0.0;

float area=0.0;

printf("please input radius ：")

scanf("%f",&radius);

circle=2*pai*radius;

area=pai*radius*radius;

printf("circle is ");

printf("%f",circle)

printf("area is ");

printf("%f",area);

}

呵呵，好久不写C了，连TURBEC 都删了，你调试一下，看看对吗