C++ Math isfinite()

The function determines the value whether it is finite or not. It should not be NaN or infinite value. If the number is finite, it returns 1 otherwise 0.

Note: A finite value is a value that is neither NAN nor infinite.

Syntax

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

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

Parameter

x: It is a floating point value.

Return value

Parameter(x)	Return value
Finite value	1
NAN or infinite value	0

Example 1

Let's see the simple example when the value of x is 10.

#include <iostream>
#include<math.h>
using namespace std;
int main()
{
    int x=10;
    cout<<"value of x is : "<<x<<'\n';
    cout<<"isfinite(x) : "<<isfinite(x);
    return 0;
}

Output:

value of x is : 10
isfinite(x) : 1

In this example, infinite() function determines that value of x is finite. Therefore, it returns 1.

Example 2

Let's see another simple example.

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

Output:

value of x is : -nan
isfinite(x) : 0

In this example, isfinite() function determines that x is a Not a Number. Therefore, it returns 0.

Example 3

Let's see the simple example when the value of x is 1.0/0.0.

#include <iostream>
#include<math.h>
using namespace std;
int main()
{
    float x=1.0/0.0;
    cout<<"value of x is : "<<x<<'\n';
    cout<<"isfinite(x) : "<<isfinite(x);
    return 0;
}

Output: