C语言数学函数ceil(), floor(), round()

用法：

#include

double ceil(double x);

double floor(double x);

double round(double x);

ceil(x)返回不小于x的最小整数值（然后转换为double型）。

floor(x)返回不大于x的最大整数值。

round(x)返回x的四舍五入整数值。

给个例子test.c：

#include

#include

int main(int argc, const char *argv[])

{

float num = 1.4999;

printf("ceil(%f) is %f\n", num, ceil(num));

printf("floor(%f) is %f\n", num, floor(num));

printf("round(%f) is %f\n", num, round(num));

return 0;

}
编译：$cc test.c -lm

执行：$./a.out

ceil(1.499900) is 2.000000

floor(1.499900) is 1.000000

round(1.499900) is 1.000000