nearbyint
函数 <cmath> <ctgmath>| C99 | double nearbyint (double x);
float nearbyintf (float x); long double nearbyintl (long double x); |
| C++11 | double nearbyint (double x);
float nearbyint (float x); long double nearbyint (long double x); double nearbyint (T x); // additional overloads for integral types |
舍入到最近的整数值
使用fegetround指定的舍入方向将x舍入为整数值。
这个函数不会引发FE_INEXACT异常。请参阅rint以获取可执行此功能的等效函数。
| C99 | 头文件<tgmath.h> 提供了该函数的类型泛型宏版本。 |
| C++11 | 这个头文件(<cmath>)为整型提供了额外的重载:
这些重载有效地在计算之前将x转换为double(在T是任何整型时定义)。
|
☲ 参数
x
舍入的值
☉ 返回值
x舍入到附近整数的值(作为浮点值)。
☣ 示例
/* nearbyint example */
#include <stdio.h> /* printf */
#include <fenv.h> /* fegetround, FE_* */
#include <math.h> /* nearbyint */
int main ()
{
printf ("rounding using ");
switch (fegetround()) {
case FE_DOWNWARD: printf ("downward"); break;
case FE_TONEAREST: printf ("to-nearest"); break;
case FE_TOWARDZERO: printf ("toward-zero"); break;
case FE_UPWARD: printf ("upward"); break;
default: printf ("unknown");
}
printf (" rounding:\n");
printf ( "nearbyint (2.3) = %.1f\n", nearbyint(2.3) );
printf ( "nearbyint (3.8) = %.1f\n", nearbyint(3.8) );
printf ( "nearbyint (-2.3) = %.1f\n", nearbyint(-2.3) );
printf ( "nearbyint (-3.8) = %.1f\n", nearbyint(-3.8) );
return 0;
}
|
可能输出:
Rounding using to-nearest rounding: nearbyint (2.3) = 2.0 nearbyint (3.8) = 4.0 nearbyint (-2.3) = -2.0 nearbyint (-3.8) = -4.0 |
🍄 另请参阅
| ceil | 向上舍入(function ) |
| floor | 向下舍入(function ) |
| trunc | 截断(function ) |
| rint | 舍入并强制转换为整数(function ) |
| round | 就近舍入(function ) |