C++

Reference

<cmath> (math.h)

macro
<cmath> <ctgmath>

isfinite

macro
isfinite(x)
function
bool isfinite (float x);bool isfinite (double x);bool isfinite (long double x);
Is finite value
Returns whether x is a finite value.

A finite value is any floating-point value that is neither infinite nor NaN (Not-A-Number).

In C, this is implemented as a macro that returns an int value. The type of x shall be float, double or long double.
In C++, it is implemented with function overloads for each floating-point type, each returning a bool value.

Parameters

x
A floating-point value.

Return value

A non-zero value (true) if x is finite; and zero (false) otherwise.

Example

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/* isfinite example */ #include <stdio.h> /* printf */ #include <math.h> /* isfinite, sqrt */ int main() { printf ("isfinite(0.0) : %d\n",isfinite(0.0)); printf ("isfinite(1.0/0.0) : %d\n",isfinite(1.0/0.0)); printf ("isfinite(-1.0/0.0) : %d\n",isfinite(-1.0/0.0)); printf ("isfinite(sqrt(-1.0)): %d\n",isfinite(sqrt(-1.0))); return 0; }

Output:
 isfinite(0.0) : 1 isfinite(1.0/0.0) : 0 isfinite(-1.0/0.0) : 0 isfinite(sqrt(-1.0)): 0


See also

isinf
Is infinity (macro/function)
isnan
Is Not-A-Number (macro/function)
isnormal
Is normal (macro/function)
fpclassify
Classify floating-point value (macro/function)