#        
## Overview
A number that can be counted is called a **finite number**. The **`isFinite()` function** is used to check if the number is finite. 

The figure below shows the visual representation of the `isFinite()` function:

>Note: Import `std.math` in your code to use the `isFinite()` function. We  can import it: </br>`import std.math`
# 
## Syntax
```D
bool isFinite(number)
```
## Parameter
This function requires the number as a parameter.

## Return value
This function returns `true` if the value is `finite`. Otherwise, it returns `false`. 

> Note: `NaN` is not considered to be finite.

## Example
The following example shows how to use `isFinite()` in D:

import core.stdc.stdio;
import std.stdio;
//header required for function
import std.math;

int main()
{
    //integer
    writeln ("The value of isFinite(4.0) : ",isFinite(4.0));

    //positive double value
    writeln ("The value of isFinite(2.56) : ",isFinite(2.56));

    //negative double value
    writeln ("The value of isFinite(-2.56) : ",isFinite(-2.56));

    //zero
    writeln ("The value of isFinite(0.0) : ",isFinite(0.0));

    //infinity
    writeln ("The value of isFinite(real.infinity) : ",isFinite(real.infinity));
    writeln ("The value of isFinite(-real.infinity) : ",isFinite(-real.infinity));
    
    //nan
    writeln ("The value of isFinite(real.nan) : ",isFinite(real.nan));
    writeln ("The value of isFinite(-real.nan) : ",isFinite(-real.nan));
    return 0;
}

## Explanation
Here is a line-by-line explanation of the code above:

*  **Line 4**: We add `std.math` library which is required to use `isFinite()` function.
*  **Line 9**: We check if the integer `4` is finite or not using the `isFinite()` function.
*   **Line 12**: We check if the positive double value `2.56` is finite or not using the `isFinite()` function.
*   **Line 15**: We check if the negative double value `-2.56` is finite or not using the `isFinite()` function.
*   **Line 18**: We check if the `zero` is finite or not using the `isFinite()` function.
*   **Lines 21 to 22**: We check if the positive infinity and negative infinity are finite or not using the `isFinite()` function.

-  **Lines 25 to 26**: We check if the positive `NaN` and negative `NaN` are finite or not using the `isFinite()` function.

What is the isFinite() function in D?

Overview

Syntax

Parameter

Return value

Example

Explanation