#        
## Overview
The **`fabs()`** function in C++ is used to return the absolute value of an argument passed to the function.

The `fabs()` function is defined in the `cmath` header file.

Mathematically, it is represented as:
$fabs(num) = |num|$

## Syntax
```
fabs(double num)
```

## Parameter value 
The `fabs()` function takes a single parameter value which is a number of any type: double, float, or long double.

## Return value
The `fabs()` function returns the absolute value of the number passed to it as an argument.

## Example 1
Let's use the `fabs()` function for `double` numbers:


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

int main() {
  int result1; 
  int result2;
  // for a negative double
  double x = -10.25, result;
  // for a positve double
  double y = 10.25;


  result1 = fabs(x);
  result2 = fabs(y);

  cout << "fabs(" << x << ") = |" << x << "| = " << result1<<endl;
  cout << "fabs(" << y << ") = |" << y << "| = " << result2;
  return 0;
}

## Code Explanation
* **Line 6–7**: We create `int` variables `result1` and `result2`.
* **Line 9–11**: We create `double` variables `x` and `y`.
* **Line 14–15**: Using the `fabs()` function, we take the absolute value of `x` and `y` variables and assign the outputs respectively to variables `result1` and `result2`.
* **Line 17 & 18**: we printed the variables `result1` and `result2`.


## Example 2

Let's use the `fabs()` function for `float` numbers:

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

int main() {
  int result1; 
  int result2;
  // for a negative float
  float x = -3.5f, result;
  // for a positve float
  float y = 3.5f;


  result1 = fabs(x);
  result2 = fabs(y);

  cout << "fabs(" << x << ") = |" << x << "| = " << result1<<endl;
  cout << "fabs(" << y << ") = |" << y << "| = " << result2;
  return 0;
}

## Example 3

Let's use the `fabs()` function for `long double` numbers:

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

int main() {
  int result1; 
  int result2;
  // for a negative long double 
  long double  x = -1.256, result;
  // for a positve long double 
  long double  y = 1.256;


  result1 = fabs(x);
  result2 = fabs(y);

  cout << "fabs(" << x << ") = |" << x << "| = " << result1<<endl;
  cout << "fabs(" << y << ") = |" << y << "| = " << result2;
  return 0;
}

What is the fabs() function in C++?

fabs() in C++ returns the absolute value of a number, working with double, float, or long double types.