R - Basic Syntax

As a convention, we will start learning R programming by writing a "Hello, World!" program. Depending on the needs, you can program either at R command prompt or you can use an R script file to write your program. Let s check both one by one.

R Command Prompt

Once you have R environment setup, then it’s easy to start your R command prompt by just typing the following command at your command prompt −

$ R

This will launch R interpreter and you will get a prompt > where you can start typing your program as follows −

> myString <- "Hello, World!"
> print ( myString)
[1] "Hello, World!"

Here first statement defines a string variable myString, where we assign a string "Hello, World!" and then next statement print() is being used to print the value stored in variable myString.

R Script File

Usually, you will do your programming by writing your programs in script files and then you execute those scripts at your command prompt with the help of R interpreter called Rscript. So let s start with writing following code in a text file called test.R as under −

# My first program in R Programming
myString <- "Hello, World!"

print ( myString)

$ Rscript test.R 

[1] "Hello, World!"

# My first program in R Programming

if(FALSE) {
   "This is a demo for multi-pne comments and it should be put inside either a 
      single OR double quote"
}

myString <- "Hello, World!"
print ( myString)

[1] "Hello, World!"