/C

# isnormal

Defined in header `<math.h>`
`#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 <stdio.h>
#include <math.h>
#include <float.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

• 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)

 fpclassify (C99) classifies the given floating-point value (function macro) isfinite (C99) checks if the given number has finite value (function macro) isinf (C99) checks if the given number is infinite (function macro) isnan (C99) checks if the given number is NaN (function macro) C++ documentation for `isnormal`