C 参考手册
- C 语言
- C 关键词
- 预处理器
- C 标准库头文件
- 类型支持
- 程序支持工具
- 变参数函数
- 错误处理
- 动态内存管理
- 日期和时间工具
- 字符串库
- 算法
- 数值
- 常用数学函数
- MATH_ERRNO, MATH_ERREXCEPT, math_errhandling
- log, logf, logl
- log10, log10f, log10l
- log1p, log1pf, log1pl
- log2, log2f, log2l
- cbrt, cbrtf, cbrtl
- fmax, fmaxf, fmaxl
- fmin, fminf, fminl
- fdim
- NAN
- exp, expf, expl
- exp2, exp2f, exp2l
- expm1, expm1f, expm1l
- fmod, fmodf, fmodl
- remainder, remainderf, remainderl
- remquo, remquof, remquol
- fma, fmaf, fmal
- div, ldiv, lldiv, imaxdiv
- fabs, fabsf, fabsl
- sqrt, sqrtf, sqrtl
- sin, sinf, sinl
- abs, labs, llabs, imaxabs
- hypot, hypotf, hypotl
- pow, powf, powl
- cos, cosf, cosl
- tan, tanf, tanl
- asin, asinf, asinl
- acos, acosf, acosl
- atan, atanf, atanl
- atan2, atan2f, atan2l
- sinh, sinhf, sinhl
- cosh, coshf, coshl
- tanh, tanhf, tanhl
- asinh, asinhf, asinhl
- acosh, acoshf, acoshl
- atanh, atanhf, atanhl
- erf, erff, erfl
- erfc, erfcf, erfcl
- lgamma, lgammaf, lgammal
- tgamma, tgammaf, tgammal
- ceil, ceilf, ceill
- floor, floorf, floorl
- round, roundf, roundl, lround, lroundf, lroundl, llround, llroundf, llroundl
- trunc, truncf, truncl
- nearbyint, nearbyintf, nearbyintl
- rint, rintf, rintl, lrint, lrintf, lrintl, llrint, llrintf, llrintl
- ldexp, ldexpf, ldexpl
- scalbn, scalbnf, scalbnl, scalbln, scalblnf, scalblnl
- ilogb, ilogbf, ilogbl
- logb, logbf, logbl
- frexp, frexpf, frexpl
- modf, modff, modfl
- nextafter, nextafterf, nextafterl, nexttoward, nexttowardf, nexttowardl
- copysign, copysignf, copysignl
- fpclassify
- isfinite
- isinf
- isnan
- isnormal
- signbit
- isgreater
- isgreaterequal
- isless
- islessequal
- islessgreater
- isunordered
- float_t, double_t
- HUGE_VALF, HUGE_VAL, HUGE_VALL
- INFINITY
- FP_NORMAL, FP_SUBNORMAL, FP_ZERO, FP_INFINITE, FP_NAN
- 浮点环境
- 伪随机数生成
- 复数算术
- 泛型数学
- 文件输入/输出
- 本地化支持
- 原子操作库
- 线程支持库
- 实验性 C 标准库
- 有用的资源
- 符号索引
- 注释
fpclassify
| 定义于头文件 <math.h>
|
||
| #define fpclassify(arg) /* implementation defined */ |
(C99 起) | |
归类浮点值 arg 到下列类别中：零、非正规、正规、无穷大、 NaN 或实现定义类别。该宏返回整数值。
忽略 FLT_EVAL_METHOD ：即使以多于参数类型的范围和精度对它求值，首先仍将它转换到其语义类型，然后分类基于该类型：正规的 long double 值可能在转换到 double 时变为非正规，而在转换到 float 时变为零。
参数
| arg | - | 浮点值 |
返回值
指明 arg 类别的 FP_INFINITE 、 FP_NAN 、 FP_NORMAL 、 FP_SUBNORMAL 、 FP_ZERO 或实现定义类型之一。
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