Why functions organize code in R Programming - Challenge Your Understanding

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this R function call?

Consider the following R code that defines a function and then calls it. What will be printed?

R Programming

greet <- function(name) {
  message <- paste("Hello," , name)
  return(message)
}

result <- greet("Alice")
print(result)

A Error: object 'message' not found

B [1] "greet Alice"

C [1] "Hello Alice"

D [1] "Hello, Alice"

💡 Hint

Look at how the paste function combines strings with a comma and a space.

The paste function combines "Hello," and "Alice" with a space by default, so the output is "Hello, Alice". The function returns this string, which is then printed.

🧠 Conceptual

intermediate

Why use functions to organize code?

Which of the following is the main reason to use functions in R programming?

A To repeat the same code multiple times without rewriting it

B To make the program run faster by skipping lines

C To avoid using variables

D To make the code harder to read

💡 Hint

Think about how functions help avoid repeating yourself.

Functions let you write a block of code once and use it many times, which saves effort and reduces mistakes.

🔧 Debug

advanced

Identify the error in this function

What error will this R code produce when run?

R Programming

add_numbers <- function(a, b) {
  sum <- a + b
  print(sum)
}

result <- add_numbers(3)

A Error: object 'sum' not found

B Error: unexpected symbol in "result <- add_numbers(3)"

C Error: argument "b" is missing, with no default

D No error, prints 3

💡 Hint

Check how many arguments the function expects and how many are given.

The function add_numbers requires two arguments, but only one is provided, causing an error about a missing argument.

📝 Syntax

advanced

Which option correctly defines a function in R?

Choose the correct syntax to define a function named 'square' that returns the square of a number x.

A function square(x) { return x * x }

B square <- function(x) { return(x * x) }

C square = function x { x * x }

D def square(x): return x * x

💡 Hint

Remember how functions are assigned in R using the <- operator.

In R, functions are assigned to names using <- and defined with function(). Option B follows this syntax correctly.

🚀 Application

expert

How many times is the message printed?

What will be the output count of the following R code?

R Programming

print_message <- function() {
  print("Hello")
}

for(i in 1:3) {
  print_message()
}

print_message()

A 4 times

B 3 times

C 1 time

D Error: function not found

💡 Hint

Count how many times the function is called inside and outside the loop.

The function print_message is called 3 times inside the loop and once after the loop, so it prints "Hello" 4 times.