# C++ fabs()

The `fabs()` function in C++ returns the absolute value of the argument. It is defined in the cmath header file.

Mathematically, `fabs(num) = |num|`.

### Example

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

int main() {

// get absolute value of -5.5
cout << fabs(-5.5);

return 0;
}

// Output: 5.5``````

## fabs() Syntax

The syntax of the `fabs()` function is:

``fabs(double num);``

## fabs() Parameters

The `fabs()` function takes the following parameter:

• num - a floating point number whose absolute value is returned. It can be of the following types:
• `double`
• `float`
• `long double`

## fabs() Return Value

The `fabs()` function returns:

• the absolute value of num i.e. `|num|`

## fabs() Prototypes

The prototypes of `fabs()` as defined in the cmath header file are:

``````double fabs(double num);

float fabs(float num);

long double fabs(long double num);

// for integral type
double fabs(T num);``````

Note: The `fabs()` function is identical to the cmathabs() function.

## Example 1: C++ fabs()

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

int main() {
double num = -10.25, result;

result = fabs(num);

cout << "fabs(" << num << ") = |" << num << "| = " << result;

return 0;
}``````

Output

`fabs(-10.25) = |-10.25| = 10.25`

## Example 2: C++ fabs() for Integral Types

``````#include <iostream>
#include <cmath>

using namespace std;

int main() {
int num = -23;
double result;

result = fabs(num);

cout << "fabs(" << num << ") = |" << num << "| = " << result;

return 0;
}``````

Output

`fabs(-23) = |-23| = 23`