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在头文件<math.h>中定义



float       floorf( float arg );

(1)

(自 C99)

double      floor( double arg );

(2)


long double floorl( long double arg );

(3)

(自 C99)

在头文件 <tgmath.h>中定义



#define floor( arg )

(4)

(自 C99)

1-3）计算不大于arg的最大整数值。

4）类型 - 通用宏：如果arg的类型为long double，则称为floorl。 否则，如果arg具有整数类型或类型double，则调用floor。 否则，floorf被调用。

参数

arg

-

floating point value

返回值

如果没有发生错误，则返回不大于arg的最大整数值，即⌊arg⌋。

返回值

看法

错误处理

按照math_errhandling中的指定报告错误。

如果实现支持IEEE浮点运算（IEC 60559），

当前的舍入模式不起作用。

如果arg为±∞，则返回，未修改

如果arg为±0，则返回，未修改

如果arg是NaN，则返回NaN

注意

在四舍五入非整数有限值时，FE_INEXACT可能（但不是必须）引发。

最大的可表示浮点值是所有标准浮点格式中的精确整数，因此该函数不会自行溢出; 但是当存储在整型变量中时，结果可能会溢出任何整数类型（包括intmax_t）。

例

#include <math.h>#include <stdio.h>int main(void){    printf("floor(+2.7) = %+.1f\n", floor(2.7));    printf("floor(-2.7) = %+.1f\n", floor(-2.7));    printf("floor(-0.0) = %+.1f\n", floor(-0.0));    printf("floor(-Inf) = %+f\n",   floor(-INFINITY));}

可能的输出：

floor(+2.7) = +2.0floor(-2.7) = -3.0floor(-0.0) = -0.0floor(-Inf) = -inf

参考

  • C11标准（ISO / IEC 9899：2011）：

    • 7.12.9.2 floor 功能（p：251）

    • 7.25类型通用数学<tgmath.h>（p：373-375）

    • F.10.6.2 floor 功能（p：526）

  • C99标准（ISO / IEC 9899：1999）：

    • 7.12.9.2 floor 功能（p：232）

    • 7.22类型通用数学<tgmath.h>（p：335-337）

    • F.9.6.2 floor 功能（p：463）

  • C89 / C90标准（ISO / IEC 9899：1990）：

    • 4.5.6.3 floor 功能

扩展内容

ceilceilfceill（C99）（C99）

计算不小于给定值的最小整数（函数）

trunctruncftruncl（C99）（C99）（C99）

四舍五入到最接近的整数，其大小不超过给定值（函数）

roundlroundllround（C99）（C99）（C99）

舍入到最接近的整数，在中途情况下从零开始舍去（函数）

| 用于floor的C ++文档 |

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