fpclassify()函数在C的标头math.h标头和C++的cmath库中定义。此函数用于获取与分类宏常量之一(取决于x的值)匹配的int类型的值。
句法:
int fpclassify(int x);
int fpclassify(float x);
int fpclassify(double x);
int fpclassify(long double x);
参数:此方法接受参数x ,该参数x是与该方法的宏常量之一匹配的值。它可以是整数,浮点数,双精度型或长双精度型。
返回值:该函数返回宏常量的整数值,如下所示:
- FP_INFINITE :当指定的值是正无穷大或负无穷大时
- FP_NAN :当指定的值不是数字时
- FP_ZERO :当指定值为零时。
- FP_SUBNORMAL :当指定值是正或负非正规化值时
- FP_NORMAL :当指定值是正或负归一化非零值时
下面的示例演示fpclassify()方法的用法:
// C++ program to demonstrate
// the use of fpclassify() method
#include
#include
using namespace std;
// Function to implement fpclassify() method
void fpclassification(double x)
{
// fpclassify() method
switch (fpclassify(x)) {
// For the data to be infinite
case FP_INFINITE:
cout << "Infinite Number \n";
break;
// For the data to be not defined
// as in divide by zero
case FP_NAN:
cout << "Not a Number \n";
break;
// For the data to be zero
case FP_ZERO:
cout << "Zero \n";
break;
// For the data to be subnormal
case FP_SUBNORMAL:
cout << "Subnormal value \n";
break;
// For the data to be normal
case FP_NORMAL:
cout << "Normal value \n";
break;
// For the data to be invalid
default:
cout << "Invalid number \n";
}
}
// Driver code
int main()
{
// Example 1
double a = 1.0 / 0.0;
cout << "For 1.0/0.0: ";
fpclassification(a);
// Example 2
double b = 0.0 / 0.0;
cout << "For 0.0/0.0: ";
fpclassification(b);
// Example 3
double c = -0.0;
cout << "For -0.0: ";
fpclassification(c);
// Example 4
double d = 1.0;
cout << "For 1.0: ";
fpclassification(d);
return 0;
}
输出:
For 1.0/0.0: Infinite Number
For 0.0/0.0: Not a Number
For -0.0: Zero
For 1.0: Normal value
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