Explore the basics of the R language, such as variables, operators, loops, and functions, and solve a few challenges.

Become an R Developer

This module will get us up to speed on R programming and assumes no prior knowledge of the language. We’ll start with the basics of R, such as variables, data types, operators, etc., and work our way up to advanced concepts like functions, classes, and exception handling. We’ll also go through some challenges to enhance our hands-on experience. By the time we’re done, we’ll be able to write detailed, useful code in R.

Learn R from Scratch

Sometimes while we are writing a program, we may want to take input from the user who is actually using our program. We design tasks so that they run on any input that the user may give. 

Take the example of a calculator. We put some input into it and tell it what to do with the input. It performs the respective task and displays the result.

Now suppose we are also creating a calculator that performs only **addition**.

Let's have a look at an example:

In the illustration, above we take two inputs from the user, perform a certain task on it and then display the result on the console.

# Using `readLines()` Function to Get User Input

The `readLines()` function **reads** a line from the console, this is referred as `stdin` file in R. The data fetched through this function can be stored in a variable and later used by the program. 

## Steps for fetching data using `STDIN`
1. First, fetch the file using
```
input <- file("stdin")
```
2. Then use the function `readLines()`
```r
UserInput <- readLines(input, <numberOfInputs>)
# Here the variable `UserInput` is a list and each of its elements can be accessed using square brackets.
```

Let's look at the code for fetching data from a user and then passing it to a function.

> Follow the following steps for executing the code below: 
> * Click on `>_ STDIN` and enter two values on separate lines. The first number should be typed in on the first line and the second number on the second line.
> * Then click `RUN`.

In this lesson, we will learn about getting data from the user.

Entering Data from the Keyboard