FP_NORMAL, FP_SUBNORMAL, FP_ZERO, FP_INFINITE, FP_NAN
来自cppreference.com
| 定义于头文件 <math.h>
|
||
| #define FP_NORMAL /*implementation defined*/ |
(C99 起) | |
| #define FP_SUBNORMAL /*implementation defined*/ |
(C99 起) | |
| #define FP_ZERO /*implementation defined*/ |
(C99 起) | |
| #define FP_INFINITE /*implementation defined*/ |
(C99 起) | |
| #define FP_NAN /*implementation defined*/ |
(C99 起) | |
FP_NORMAL 、 FP_SUBNORMAL 、 FP_ZERO 、 FP_INFINITE 、 FP_NAN 宏各代表一个独自的浮点数类别。它们都展开成整数常量表达式。
| 常量 | 解释 |
FP_NORMAL
|
指示值为正规，即不是无穷大、非正规、非数或零 |
FP_SUBNORMAL
|
指示值为非正规 |
FP_ZERO
|
指示值为正或负零 |
FP_INFINITE
|
指示值无法以底层类型表示（正或负无穷大） |
FP_NAN
|
指示值是非数（ NaN ） |
示例
运行此代码
#include <stdio.h> #include <math.h> #include <float.h> const char *show_classification(double x) { switch(fpclassify(x)) { case FP_INFINITE: return "Inf"; case FP_NAN: return "NaN"; case FP_NORMAL: return "normal"; case FP_SUBNORMAL: return "subnormal"; case FP_ZERO: return "zero"; default: return "unknown"; } } int main(void) { printf("1.0/0.0 is %s\n", show_classification(1/0.0)); printf("0.0/0.0 is %s\n", show_classification(0.0/0.0)); printf("DBL_MIN/2 is %s\n", show_classification(DBL_MIN/2)); printf("-0.0 is %s\n", show_classification(-0.0)); printf(" 1.0 is %s\n", show_classification(1.0)); }
输出：
1.0/0.0 is Inf 0.0/0.0 is NaN DBL_MIN/2 is subnormal -0.0 is zero 1.0 is normal
引用
- C11 standard (ISO/IEC 9899:2011):
- 7.12/6 FP_NORMAL, ... (p: 232)
- C99 standard (ISO/IEC 9899:1999):
- 7.12/6 FP_NORMAL, ... (p: 213)
参阅
| (C99) |
对给定的浮点值分类 (宏函数) |
