##### cppreference.com

##### Search

Create account

##### Namespaces

- Page
- Discussion

##### Variants

##### Views

- View
- Edit
- History

##### Actions

# isinf

From cppreference.com
< c‎ | numeric‎ | math

Defined in header `<math.h>` |  |
#define isinf(arg) /* implementation defined */ |  | (since C99)

Determines if the given floating point number `arg` is positive or negative infinity. The macro returns an integral value.

### [edit] Parameters

arg | - | floating point value

### [edit] Return value

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

### [edit] Example

Run this code

    #include <stdio.h>
    #include <math.h>
    #include <float.h>

    int main(void)
    {
        printf("isinf(NAN)         = %d\n", isinf(NAN));
        printf("isinf(INFINITY)    = %d\n", isinf(INFINITY));
        printf("isinf(0.0)         = %d\n", isinf(0.0));
        printf("isinf(DBL_MIN/2.0) = %d\n", isinf(DBL_MIN/2.0));
        printf("isinf(1.0)         = %d\n", isinf(1.0));

        return 0;
    }

Possible output:

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

### [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]
isnan (C99) | checks if the given number is NaN (function) [edit]
isnormal (C99) | checks if the given number is normal (function) [edit]
C++ documentation for isinf

Retrieved from "http://en.cppreference.com/mwiki/index.php?title=c/numeric/math/isinf&oldid=70148"