R - Basic Syntax
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)
Save the above code in a file test.R and execute it at Linux command prompt as given below. Even if you are using Windows or other system, syntax will remain same.
$ Rscript test.R
When we run the above program, it produces the following result.
[1] "Hello, World!"
Comments
Comments are like helping text in your R program and they are ignored by the interpreter while executing your actual program. Single comment is written using # in the beginning of the statement as follows −
# My first program in R Programming
R does not support multi-line comments but you can perform a trick which is something as follows −
if(FALSE) {
"This is a demo for multi-line comments and it should be put inside either a
single OR double quote"
}
myString <- "Hello, World!"
print ( myString)
[1] "Hello, World!"
Though above comments will be executed by R interpreter, they will not interfere with your actual program. You should put such comments inside, either single or double quote.