Variables in R Programming

 Variables are used to store the information to be manipulated and referenced in the R program. The R variable can store an atomic vector, a group of atomic vectors, or a combination of many R objects.

Language like C++ is statically typed, but R is a dynamically typed, means it check the type of data type when the statement is run. A valid variable name contains letter, numbers, dot and underlines characters. A variable name should start with a letter or the dot not followed by a number.

Name of variable	Validity	Reason for valid and invalid
_var_name	Invalid	Variable name can't start with an underscore(_).
var_name, var.name	Valid	Variable can start with a dot, but dot should not be followed by a number. In this case, the variable will be invalid.
var_name%	Invalid	In R, we can't use any special character in the variable name except dot and underscore.
2var_name	Invalid	Variable name cant starts with a numeric digit.
.2var_name	Invalid	A variable name cannot start with a dot which is followed by a digit.
var_name2	Valid	The variable contains letter, number and underscore and starts with a letter.

Assignment of variable

In R programming, there are three operators which we can use to assign the values to the variable. We can use leftward, rightward, and equal_to operator for this purpose.

There are two functions which are used to print the value of the variable i.e., print() and cat(). The cat() function combines multiples values into a continuous print output.

1. # Assignment using equal operator.  
2. variable.1 = 124             
3.   
4. # Assignment using leftward operator.  
5. variable.2 <- "Learn R Programming"     
6.   
7. # Assignment using rightward operator.     
8. 133L -> variable.3             
9.   
10. print(variable.1)  
11. cat ("variable.1 is ", variable.1 ,"\n")  
12. cat ("variable.2 is ", variable.2 ,"\n")  
13. cat ("variable.3 is ", variable.3 ,"\n")  

When we execute the above code in our R command prompt, it will give us the following output:

Data types of variable

R programming is a dynamically typed language, which means that we can change the data type of the same variable again and again in our program. Because of its dynamic nature, a variable is not declared of any data type. It gets the data type from the R-object, which is to be assigned to the variable.

We can check the data type of the variable with the help of the class() function. Let's see an example:

1. variable_y<- 124  
2. cat("The data type of variable_y is ",class(variable_y),"\n")  
3.   
4. variable_y<- "Learn R Programming"     
5. cat("  Now the data type of variable_y is ",class(variable_y),"\n")  
6.   
7. variable_y<- 133L   
8. cat("   Next the data type of variable_y becomes ",class(variable_y),"\n")  

When we execute the above code in our R command prompt, it will give us the following output: