Namespaces
Variants
Views
Actions

isfinite

From cppreference.com
< c‎ | numeric‎ | math
 
 
 
Common mathematical functions
Functions
Basic operations
(C99)
(C99)
(C99)
(C99)(C99)(C99)(C23)
Maximum/minimum operations
(C99)
(C99)
Exponential functions
(C23)
(C99)
(C99)
(C23)
(C23)

(C99)
(C99)(C23)
(C23)
(C23)
Power functions
(C99)
(C23)
(C23)

(C99)
(C23)
(C23)
Trigonometric and hyperbolic functions
(C23)
(C23)
(C23)
(C23)
(C99)
(C99)
(C99)
Nearest integer floating-point
(C99)(C99)(C99)
(C99)

(C99)(C99)(C99)
(C23)(C23)(C23)(C23)
Floating-point manipulation
(C99)(C99)
(C99)(C23)
(C99)
Narrowing operations
(C23)
(C23)
(C23)
(C23)
(C23)
(C23)
Quantum and quantum exponent
Decimal re-encoding functions
Total order and payload functions
Classification
isfinite
(C99)
(C99)
(C99)
(C99)
(C23)
Error and gamma functions
(C99)
(C99)
(C99)
(C99)
Types
Macro constants
Special floating-point values
(C99)(C23)
Arguments and return values
Error handling
Fast operation indicators
 
Defined in header <math.h>
#define isfinite(arg) /* implementation defined */
(since C99)

Determines if the given floating-point number arg has finite value i.e. it is normal, subnormal or zero, but not infinite or 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.

Contents

[edit] Parameters

arg - floating-point value

[edit] Return value

Nonzero integral value if arg has finite value, 0 otherwise.

[edit] Example

#include <float.h>
#include <math.h>
#include <stdio.h>
 
int main(void)
{
    printf("isfinite(NAN)         = %d\n", isfinite(NAN));
    printf("isfinite(INFINITY)    = %d\n", isfinite(INFINITY));
    printf("isfinite(0.0)         = %d\n", isfinite(0.0));
    printf("isfinite(DBL_MIN/2.0) = %d\n", isfinite(DBL_MIN / 2.0));
    printf("isfinite(1.0)         = %d\n", isfinite(1.0));
    printf("isfinite(exp(800))    = %d\n", isfinite(exp(800)));
}

Possible output:

isfinite(NAN)         = 0
isfinite(INFINITY)    = 0
isfinite(0.0)         = 1
isfinite(DBL_MIN/2.0) = 1
isfinite(1.0)         = 1
isfinite(exp(800))    = 0

[edit] References

  • C23 standard (ISO/IEC 9899:2024):
  • 7.12.3.2 The isfinite macro (p: TBD)
  • C17 standard (ISO/IEC 9899:2018):
  • 7.12.3.2 The isfinite macro (p: TBD)
  • C11 standard (ISO/IEC 9899:2011):
  • 7.12.3.2 The isfinite macro (p: 236)
  • C99 standard (ISO/IEC 9899:1999):
  • 7.12.3.2 The isfinite macro (p: 216-217)

[edit] See also

classifies the given floating-point value
(function macro) [edit]
(C99)
checks if the given number is infinite
(function macro) [edit]
(C99)
checks if the given number is NaN
(function macro) [edit]
checks if the given number is normal
(function macro) [edit]
C++ documentation for isfinite