C语言这题如何不四舍五入

Question

当r=1,h=1的时候
我想要输出的结果是3.141,而不是3.142
如何能做到得出的结果不四舍五入
#include <stdio.h>
#define PI 3.14159265
int main()
{
float r,h,s,v;
printf ("r= ");
scanf ("%f",&r);
printf ("h= ");
scanf ("%f",&h);
s=PI*r*r;
v=s*h;
printf ("底面积=%.3lf\n",s);
printf ("体积=%.3lf\n",v);
}
求完整的编程

Answer 1

int(1000 * num)/1000.0

/*
r = 1
h = 1
底面积 = 3.141
体积 = 3.141
Press any key to continue
*/
#include <stdio.h>
#define PI 3.14159265f
int main() {
float r,h,s,v;
printf("r = ");
scanf("%f",&r);
printf ("h = ");
scanf("%f",&h);
s = PI*r*r;
v = s*h;
printf("底面积 = %.3lf\n",int(1000 * s)/1000.0);
printf("体积 = %.3lf\n",int(1000 * v)/1000.0);
return 0;
}

Answer 2

#include <stdio.h>
#define PI 3.14159265
int main()
{
float r,h,s,v;
int temp;
printf ("r= ");
scanf ("%f",&r);
printf ("h= ");
scanf ("%f",&h);
s=PI*r*r;
temp =(int)(s*1000);
s = (float)temp/1000.0;
v=s*h;
temp =(int)(v*1000);
v = (float)temp/1000.0;
printf ("底面积=%.3lf\n",s);
printf ("体积=%.3lf\n",v);
}
改成这样即可

Answer 3

简单，将pi乘以1000，然后取整，再除以1000.0；
写成表达式是:(int)(pi*1000)/1000.0

Answer 4

printf("%.3f",s);