[C / C ++ syntax] - floor function

floor () function

The floor function is a function of rounding down, returns the largest integer less than or equal to x is less than, i.e. the -infinity

Function prototype: double floor (double)

floor function is header <math.h>
For example:

#include <stdio.h>
#include <math.h>

int main(void)
{
    double a;
    while(~scanf("%lf", &a))
    {
        double ans1;
        ans1 = floor(a);
        printf("floor = %lf\n", ans1);
    }
    return 0;
}

ceil () function

ceil function of rounding up function, returns the largest integer equal to or greater than greater than x, i.e., rounding toward plus infinity

The function prototype: double ceil (double x)

ceil function is header <math.h>
For example:

#include <stdio.h>
#include <math.h>

int main(void)
{
    double a;
    while(~scanf("%lf", &a))
    {
        double ans1;
        ans1 = ceil(a);
        printf("ceil= %lf\n", ans1);
    }
    return 0;
}

round () function

round () function is a function of rounding

The function prototype: double round (double x)

round () function is header <math.h>
For example:

#include <stdio.h>
#include <math.h>

int main(void)
{
    double a;
    while(~scanf("%lf", &a))
    {
        double ans1;
        ans1 = round(a);
        printf("round = %lf\n", ans1);
    }
    return 0;
}

to sum up

Function name	Function Description	2.9	2.1	-2.9	-2.1
floor()	Downward (minus infinity) of the integral function	2.0	2.0	-3.0	-3.0
ceil()	Upward (positive infinity) of the integral function	3.0	3.0	-2	-2
round()	rounding	3.0	2.0	-3.0	-2.0