C++ Math isnan

The function verifies if the value is a NaN (Not a Number). It outputs 1 if the value is NaN, otherwise it returns 0.

Note: The NaN is a non-representable value for floating point elements such as square root of negative number or the result of 0/0.

Syntax

Suppose a number is 'x'. Syntax would be:

bool isnan(float x);
bool isnan(double x);
bool isnan(long double x);
bool isnan(integral x);

Parameter

x : It is a floating point value.

Return value

It returns 1, if x is NAN otherwise 0.

Example 1

Let's consider a straightforward scenario where the value of x equals 0.0 divided by 0.0.

#include <iostream>
#include<math.h>
using namespace std;
int main()
{
    float x=0.0/0.0;
    cout<<"value of x is : "<<x<<'\n';
    cout<<"isnan(x) : "<<isnan(x);
    return 0;
}

Output:

value of x is : -nan
isnan(x) : 1

In this instance, the isnan(x) function assesses whether the value of x is NaN, and consequently, it yields a result of 1.

Example 2

Let's consider a basic scenario where the value assigned to x is 4.3.

#include <iostream>
#include<math.h>
using namespace std;
int main()
{
    float x=4.3;
    cout<<"value of x is : "<<x<<'\n';
    cout<<"isnan(x) : "<<isnan(x);
    return 0;
}

Output:

value of x is : 4.3
isnan(x) : 0

In this instance, the isnan(x) function assesses whether the value of x is not a 'nan' (not a number) and consequently, it produces a result of 0.