輸入一個半徑？

# include <stdio.h>

# include <stdlib.h>

# define PI 3.14159

int main(void)

{

double r, c, s1, s2, v;

printf("輸入圓的半徑：\n\a");

scanf("%lf", &r);//這里有變動，雙精度浮點型（double）輸入是用%lf

c = PI * 2.0 * r;

s1 = PI * r * r;

s2 = 4.0 * s1;

v = (4 * PI * r * r * r)/3.0;

printf("周長 = %lf\n圓面積 = %lf\n球面積 = %lf\n球體積 = %lf\n", c, s1, s2, v);

return 0;

}

想保留最后兩位：可以這樣

# include <stdio.h>

# include <stdlib.h>

# define PI 3.14159

int main(void)

{

double r, c, s1, s2, v;

printf("輸入圓的半徑：\n\a");

scanf("%lf", &r);//這里有變動，雙精度浮點型（double）輸入是用%lf動 ，%.2lf

c = PI * 2.0 * r;

s1 = PI * r * r;

s2 = 4.0 * s1;

v = (4 * PI * r * r * r)/3.0;

printf("周長 = %.2lf\n圓面積 = %.2lf\n球面積 = %.2lf\n球體積 = %.2lf\n", c, s1, s2, v);//這里改動了，看看%.2lf

return 0;

}