R language Basic syntax

We'll start learning the R language programming, starting with a "Hello, World!" p rogram. D epending on your needs, you can program at the R command prompt, or you can script a program in the R language. Let's experience the differences one by one.

Command prompt

If you already have an R-language environment configured, you can easily turn on command prompts with just one click of the command

$ R

This will start the R language 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, the first statement first defines a string variable, myString, and will read "Hello, World! " Where the assignment is given, the second sentence uses the print() statement to print the contents of the variable myString.

The script file

Typically, you'll program by writing programs in a script file, and then using an R interpreter (called Rscript) at the command prompt to execute those scripts. S o let's start with a named test. W rite the following code in R's text file

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

print ( myString)

Save the above code in test. R file, executed under the Linux command prompt, as shown below. E ven if you are using Windows or other systems, the syntax will remain the same.

$ Rscript test.R 

When we run the program above, it produces the following results.

[1] "Hello, World!"

Comments

Comments can help you explain scripts in the R-language program that are ignored by the interpreter when you actually execute the program. A single comment is written at the beginning of the statement, as shown below

# My first program in R Programming

The R language does not support multi-line comments, but you can use a tip, 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)

Although the comments above will be executed by the R interpreter, they will not interfere with your actual program. B ut you have to put single or double quotes on the content.