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在头文件<math.h>中定义



float       fmaxf( float x, float y );

(1)

(自C99)

double      fmax( double x, double y );

(2)

(自C99)

long double fmaxl( long double x, long double y );

(3)

(自C99)

在头文件 <tgmath.h>中定义



#define fmax( x, y )

(4)

(自C99)

1-3）返回两个浮点参数中较大的一个，将NaN视为缺失数据（在NaN和数值之间选择数值）。

4）类型泛型宏：如果任何参数的类型为long double，则调用fmaxl。 否则，如果任何参数具有整数类型或类型为double，则调用fmax。 否则，调用fmaxf。

参数

x, y

-

floating point values

返回值

如果成功，则返回两个浮点值中较大的一个。返回的值是精确的，并不取决于任何舍入模式。

错误处理

此函数不受math_errhandling中指定的任何错误条件的约束。

如果实现支持IEEE浮点运算（IEC 60559），

  • 如果两个参数之一是NaN，则返回另一个参数的值

  • 只有两个参数都是NaN，才会返回NaN

注意

该函数不要求对零符号敏感，但有些实现还强制规定，如果一个参数为+0，另一个为-0，则返回+0。

例

#include <stdio.h>#include <math.h>
 int main(void){    printf("fmax(2,1)    = %f\n", fmax(2,1));    printf("fmax(-Inf,0) = %f\n", fmax(-INFINITY,0));    printf("fmax(NaN,-1) = %f\n", fmax(NAN,-1));}

输出：

fmax(2,1)    = 2.000000fmax(-Inf,0) = 0.000000fmax(NaN,-1) = -1.000000

参考

  • C11标准（ISO / IEC 9899：2011）：

    • 7.12.12.2 fmax函数（p：257-258）

    • 7.25类型通用数学<tgmath.h>（p：373-375）

    • F.10.9.2 fmax函数（p：530）

  • C99标准（ISO / IEC 9899：1999）：

    • 7.12.12.2 fmax函数（p：238-239）

    • 7.22类型通用数学<tgmath.h>（p：335-337）

    • F.9.9.2 fmax函数（p：466）

扩展内容

isgreater（C99）

检查第一个浮点参数是否大于第二个（函数）

fmfminfminl（C99）（C99）（C99）

确定两个浮点值中较小的一个（函数）

| fmax的C ++文档 |

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