In this shot, we will learn how to use the **`ratio_add()` function**. This template alias is used to add the two ratios.

> The `ratio_add()` function is available in `<ratio>` header file in C++.


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## What is a ratio?
A **ratio** is a representation of a fraction in which the numerator and denominator are differentiated by a colon (:) symbol. The numerator and denominator can be of `float` data type.

Let’s understand with the help of an example. Suppose that the first ratio is 1 : 3 and the second ratio is 5 : 2.
So, the result of the `ratio_add()` function on these two ratios gives the result as 17 : 6. Let’s dive into how the addition took place.

* First, we need to find the #key# LCM: Lowest Common Multiple #key# of the denominators of the two fractions which will be the denominator of the addition.

* The LCM of 3 and 2 is 6.

* Now addition = $\frac{(1*2+5*3)}{6}$ = $\frac{17}{6}$ 

## Parameters
The `ratio_add()` method takes the following parameters:
* `Ratio1`: A `ratio` object for addition.
* `Ratio2`: Another `ratio` object to perform the addition with the first `ratio` object.

## Return value
This function returns the result of addition in the simplest form.
It returns two member constants:
* `num`: The simplified numerator of the ratio after the addition of the two ratios.
* `den`: The simplified denominator of the ratio after the addition of the two ratios.

## Code
Let’s have a look at the code.


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

int main()
{ 
  typedef ratio<1, 3> ratio1;
  typedef ratio<5, 2> ratio2;

  typedef ratio_add< ratio1, ratio2 > sum;
    
  cout << "The ratio after addition is : ";
  cout << sum::num << "/" << sum::den;
  
  return 0;
}


## Explanation
* In lines 1 and 2 we imported the required header files.
* In line 5 we made a `main()` function.
* From lines 7 and 8 we declared two ratios.
* In line 10 we performed the sum of the two declared ratios by using `ratio_add()` function.
* In line 12 we displayed a message regarding the result.

* In line 13 we displayed the numerator and denominator by accessing them through the sum variable and displayed the result.


In this way, we can use the `ratio_add()` function to add two ratios and get the addition in the simplest form.



How to use the ratio_add() function in C++

What is a ratio?

Parameters

Return value

Code

Explanation