Character (string) type in R Programming - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this R code?

Consider the following R code snippet. What will it print?

R Programming

text <- "Hello, R!"
cat(substr(text, 8, 9))

A R!

B R

C R!\n

D lo

💡 Hint

Remember that substr extracts characters from start to end positions inclusive.

The substr function extracts characters from position 8 to 9. In "Hello, R!", position 8 is 'R' and position 9 is '!'. But cat prints without quotes and no newline by default, so it prints 'R!'. Option A is 'R' only, so the correct answer is A.

❓ Predict Output

intermediate

What does this R code print?

What is the output of this R code?

R Programming

text <- "Data123"
print(grepl("[0-9]", text))

A TRUE

B FALSE

C Error: invalid regular expression

D NA

💡 Hint

grepl returns TRUE if the pattern is found anywhere in the string.

The pattern "[0-9]" matches any digit. Since "Data123" contains digits, grepl returns TRUE.

🔧 Debug

advanced

Why does this R code produce an error?

This code is intended to concatenate two strings with a space. Why does it produce an error?

R Programming

str1 <- "Hello"
str2 <- 123
result <- paste(str1, str2, sep=" ")
print(result)

A Error because sep argument is invalid

B No error; output is "Hello 123"

C Error because str2 is numeric and paste requires strings

D Error because print cannot print numeric values

💡 Hint

Check how paste handles numeric arguments.

paste automatically converts numeric arguments to strings, so no error occurs. The output is "Hello 123".

❓ Predict Output

advanced

What is the output of this R code involving string splitting?

What does this R code print?

R Programming

text <- "apple,banana,carrot"
result <- strsplit(text, ",")[[1]]
print(length(result))

A 0

B 1

C Error: subscript out of bounds

D 3

💡 Hint

strsplit returns a list; extracting the first element gives the vector of split strings.

strsplit splits the string into c("apple", "banana", "carrot"), so length is 3.

🧠 Conceptual

expert

Which option correctly explains the behavior of R's character vectors?

Which statement about character vectors in R is TRUE?

A Character vectors automatically convert numbers to strings when combined.

B Character vectors store strings as linked lists internally.

C Character vectors are immutable; you cannot change individual characters inside a string element.

D Character vectors can contain elements of different types like numbers and strings.

💡 Hint

Think about how strings behave in R when you try to change a single character.

In R, strings inside character vectors are immutable; you cannot change a single character inside a string element directly.