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isnormal - cppreference.com

From cppreference.com

#define isnormal(arg) /* implementation defined */

 (since C99)

Determines if the given floating-point number arg is normal, i.e. is neither zero, subnormal, infinite, nor NaN. The macro returns an integral value.

FLT_EVAL_METHOD is ignored: even if the argument is evaluated with more range and precision than its type, it is first converted to its semantic type, and the classification is based on that.

Parameters

arg - floating-point value

Return value

Nonzero integral value if arg is normal, 0 otherwise.

Example

#include <float.h>
#include <math.h>
#include <stdio.h>
 
int main(void)
{
    printf("isnormal(NAN)         = %d\n", isnormal(NAN));
    printf("isnormal(INFINITY)    = %d\n", isnormal(INFINITY));
    printf("isnormal(0.0)         = %d\n", isnormal(0.0));
    printf("isnormal(DBL_MIN/2.0) = %d\n", isnormal(DBL_MIN / 2.0));
    printf("isnormal(1.0)         = %d\n", isnormal(1.0));
}

Output: 

isnormal(NAN)         = 0
isnormal(INFINITY)    = 0
isnormal(0.0)         = 0
isnormal(DBL_MIN/2.0) = 0
isnormal(1.0)         = 1

References

  • C23 standard (ISO/IEC 9899:2024):
  • 7.12.3.5 The isnormal macro (p: TBD)
  • C17 standard (ISO/IEC 9899:2018):
  • 7.12.3.5 The isnormal macro (p: TBD)
  • C11 standard (ISO/IEC 9899:2011):
  • 7.12.3.5 The isnormal macro (p: 237)
  • C99 standard (ISO/IEC 9899:1999):
  • 7.12.3.5 The isnormal macro (p: 217-218)

See also