isfinite() function with example in C++

C++ isfinite() function: Here, we are going to learn about the isfinite() function with example of cmath header in C++ programming language?
Submitted by IncludeHelp, on May 17, 2020

C++ isfinite() function

isfinite() function is a library function of cmath header, it is used to check whether the given value is a finite value or not? It accepts a value (float, double or long double) and returns 1 if the value is finite; 0, otherwise.

Syntax of isfinite() function:

In C99, it has been implemented as a macro,

```    macro isfinite(x)
```

In C++11, it has been implemented as a function,

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

Parameter(s):

• x – represents a value to be checked as finite value.

Return value:

The returns type of this function is bool, it returns 1 if x is a finite value; 0, otherwise.

Example:

```    Input:
float x = 10.0f;

Function call:
isfinite(x);

Output:
1
```

C++ code to demonstrate the example of isfinite() function

```// C++ code to demonstrate the example of
// isfinite() function

#include <iostream>
#include <cmath>
using namespace std;

int main()
{
cout << "isfinite(0.0): " << isfinite(0.0) << endl;
cout << "isfinite(0.0/0.0): " << isfinite(0.0 / 0.0) << endl;
cout << "isfinite(0.0/1.0): " << isfinite(0.0 / 1.0) << endl;
cout << "isfinite(1.0/0.0): " << isfinite(1.0 / 0.0) << endl;

float x = 10.0f;

// checking finite value using the condition
if (isfinite(x)) {
cout << x << " is a finite value." << endl;
}
else {
cout << x << " is not a finite value." << endl;
}

x = 10.0f / 0.0f;

if (isfinite(x)) {
cout << x << " is a finite value." << endl;
}
else {
cout << x << " is not a finite value." << endl;
}

return 0;
}
```

Output

```isfinite(0.0): 1
isfinite(0.0/0.0): 0
isfinite(0.0/1.0): 1
isfinite(1.0/0.0): 0
10 is a finite value.
inf is not a finite value.
```

Reference: C++ isfinite() function