The **`abs()`** function in C++ is used to get the absolute value of a number. The absolute value of a number is the distance of the number from 0. In other words, it is the non-negative value of the number. The absolute value of a number x is represented as |x| as shown below:

# Library
To use the `abs()` function, include the following library:
```C
#include <cstdlib>
```
# Declaration
The `abs()` function is declared as:
```C
int abs(int x);  
```
Or
```C
long int abs(long int x );  
```
Or
```C
long long int abs(long long int x);  
```
* `x`: The number whose absolute value will be calculated.

# Return value
The `abs()` function returns the absolute value of `x`.

# abs() for floating-point types
The `abs()` function in the `cstlib` header file computes the absolute value of integer data type i.e. `int`.
To calculate the absolute value of floating-point types, the `abs()` function is overloaded in the library `cmath`. The `abs()` function in `cmath` header file is declared as:
```C
double abs (double x);
```
Or
```C
float abs (float x);
```
Or
```C
long double abs (long double x);
```
Or
```C
double abs (T x);
```       

# Examples
## Example 1
Consider the code snippet below, which demonstrates the use of the `abs()` function:

#include <cstdlib>
#include <iostream>
  
using namespace std;
  
int main()
{
    int x1 = -4;
    int x2 = 0;
    int x3 = 4;

    int abs1 = abs(x1);
    cout<< "abs ( "<<x1<<" ) = "<<abs1<<endl;

    int abs2 = abs(x2);
    cout<< "abs ( "<<x2<<" ) = "<<abs2<<endl;
    
    int abs3 = abs(x3);
    cout<< "abs ( "<<x3<<" ) = "<<abs3<<endl;

    return 0;
}

## Explanation
Three integers `x1`, `x2`, and `x3` are declared in *line 8-10*. The `abs()` function is used in *line 12*, *line 15*, and *line 18* to calculate the absolute value of `x1`, `x2`, and `x3` respectively.

## Example 2
Consider the code snippet below, which demonstrates the use of the `abs()` function from `cmath` header file:

#include <cmath>
#include <iostream>
  
using namespace std;
  
int main()
{
    float x1 = -4.4;
    float x2 = 0;
    float x3 = 4.9;

    float abs1 = abs(x1);
    cout<< "abs ( "<<x1<<" ) = "<<abs1<<endl;

    float abs2 = abs(x2);
    cout<< "abs ( "<<x2<<" ) = "<<abs2<<endl;
    
    float abs3 = abs(x3);
    cout<< "abs ( "<<x3<<" ) = "<<abs3<<endl;

    return 0;
}

## Explanation
Three floats `x1`, `x2`, and `x3` are declared in *line 8-10*. The `abs()` function is used in *line 12*, *line 15*, and *line 18* to calculate the absolute value of `x1`, `x2`, and `x3` respectively.

What is abs() in C++?

The abs() function in C++ returns the non-negative value of a number, applicable to both integer and floating-point types.