Question

c语言代码，输入一个半径，求圆的周长，面积，球面积，球体积，求验证

为什么结果不对.
# include <stdio.h>
# include <stdlib.h>
# define PI 3.14159

int main(void)
{
double r, c, s1, s2, v;

printf("输入圆的半径：\n\a");
scanf("%f", &r);

c = PI * 2.0 * r;
s1 = PI * r * r;
s2 = 4.0 * s1;
v = (4 * PI * r * r * r)/3.0;

printf("周长 = %lf\n圆面积 = %lf\n球面积 = %lf\n球体积 = %lf\n", c, s1, s2, v);

return 0;
}
结果保留两位小数怎么搞？

Answer 1

# include <stdio.h>
# include <stdlib.h>
# define PI 3.14159

int main(void)
{
double r, c, s1, s2, v;

printf("输入圆的半径：\n\a");
scanf("%lf", &r);//这里有变动，双精度浮点型（double）输入是用%lf

c = PI * 2.0 * r;
s1 = PI * r * r;
s2 = 4.0 * s1;
v = (4 * PI * r * r * r)/3.0;

printf("周长 = %lf\n圆面积 = %lf\n球面积 = %lf\n球体积 = %lf\n", c, s1, s2, v);

return 0;
}

想保留最后两位：可以这样
# include <stdio.h>
# include <stdlib.h>
# define PI 3.14159

int main(void)
{
double r, c, s1, s2, v;

printf("输入圆的半径：\n\a");
scanf("%lf", &r);//这里有变动，双精度浮点型（double）输入是用%lf动 ，%.2lf

c = PI * 2.0 * r;
s1 = PI * r * r;
s2 = 4.0 * s1;
v = (4 * PI * r * r * r)/3.0;

printf("周长 = %.2lf\n圆面积 = %.2lf\n球面积 = %.2lf\n球体积 = %.2lf\n", c, s1, s2, v);//这里改动了，看看%.2lf

return 0;
}

Answer 2

scanf("%f", &r);
改为scanf("%lf", &r);
加了个小写字母 l
double的输出格式是 %lf
假如你定义的数据是 float，那么scanf("%f", &r); 就是正确的

输出两位小数， %lf.2 %.2lf 不记得是哪个了。。。。

Answer 3

你好，scanf读取double型时要用lf（第一个是小写的L）