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# isnormal

From cppreference.com
< c‎ | numeric‎ | math

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.

### [edit] Parameters

arg | - | floating point value

### [edit] Return value

Nonzero integral value if `arg` is normal, ​0​ otherwise.

### [edit] Example

Run this code

    #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

### [edit] 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)

### [edit] See also

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

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