C++ fpclassify()

The fpclassify() function in C++ returns an integer value indicating the classification of a floating-point number. It categorizes values as normal, subnormal, zero, infinite, or NaN (Not-a-Number). The function is available through the <cmath> header.

Syntax

fpclassify(x)

Parameters:

• x: A floating-point value (can be float, double, or long double).

Return value:

The fpclassify() function returns one of the following integer constants:

• FP_INFINITE: The value is positive or negative infinity.
• FP_NAN: The value is NaN (Not-a-Number).
• FP_ZERO: The value is zero.
• FP_SUBNORMAL: The value is a subnormal (denormalized) number.
• FP_NORMAL: The value is a normal finite non-zero number.

Example

The following example demonstrates various classifications using fpclassify():

#include <iostream>
#include <cmath>

using namespace std;

int main() {
  double normal = 1.5;
  double zero = 0.0;
  double inf = INFINITY;
  double nan = NAN;

  cout << "Classification of " << normal << ": ";
  if (fpclassify(normal) == FP_NORMAL) {
    cout << "Normal" << endl;
  }

  cout << "Classification of " << zero << ": ";
  if (fpclassify(zero) == FP_ZERO) {
    cout << "Zero" << endl;
  }

  cout << "Classification of inf: ";
  if (fpclassify(inf) == FP_INFINITE) {
    cout << "Infinite" << endl;
  }

  cout << "Classification of nan: ";
  if (fpclassify(nan) == FP_NAN) {
    cout << "NaN" << endl;
  }

  return 0;
}

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The output of this code is:

Classification of 1.5: Normal
Classification of 0: Zero
Classification of inf: Infinite
Classification of nan: NaN

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Codebyte Example

The following runnable example shows how to use fpclassify() with different values:

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