Integer type in R Programming - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of integer division in R?

Consider the following R code:

x <- 7L
result <- x %/% 2
print(result)

What will be printed?

R Programming

x <- 7L
result <- x %/% 2
print(result)

A 3

B Error: non-integer division

C 4

D 3.5

💡 Hint

The operator %/% performs integer division, which discards the remainder.

In R, %/% divides two numbers and returns the integer quotient by discarding any remainder. So 7 %/% 2 equals 3.

❓ Predict Output

intermediate

What is the type of an integer literal in R?

What is the output of this code?

typeof(5L)

R Programming

typeof(5L)

A "double"

B "numeric"

C "integer"

D "logical"

💡 Hint

The suffix L forces the number to be an integer type.

In R, adding L after a number makes it an integer literal. typeof(5L) returns "integer".

🔧 Debug

advanced

Why does this integer overflow happen?

Examine this R code:

large_int <- 2147483647L
result <- large_int + 1L
print(result)

What is the output and why?

R Programming

large_int <- 2147483647L
result <- large_int + 1L
print(result)

A -2147483648

B 2147483648

C NA

D Error: integer overflow

💡 Hint

R integers are 32-bit signed and wrap around on overflow.

The maximum 32-bit signed integer is 2147483647. Adding 1 causes wrap-around to -2147483648 due to overflow.

🧠 Conceptual

advanced

What happens when mixing integer and double in arithmetic?

What is the type of the result of this R expression?

typeof(5L + 2.0)

R Programming

typeof(5L + 2.0)

A "complex"

B "integer"

C "numeric"

D "double"

💡 Hint

R converts integers to doubles when mixed in arithmetic.

When an integer and a double are combined in arithmetic, R converts the integer to double. So the result is double type.

❓ Predict Output

expert

How many elements are in this integer vector after coercion?

What is the length of the vector created by this code?

vec <- c(1L, 2.5, 3L, TRUE, "4")
length(vec)

R Programming

vec <- c(1L, 2.5, 3L, TRUE, "4")
length(vec)

A 4

B 5

C 3

D Error: incompatible types

💡 Hint

All elements are coerced to a common type in c().

The vector has 5 elements. R coerces all to character because of the string "4". length() returns 5.

Practice

1. What does adding L after a number in R do?

easy

A. It makes the number an integer type.

B. It converts the number to a character string.

C. It makes the number a decimal (double) type.

D. It comments out the number in the code.

Solution

1. Step 1: Understand the role of L in R

   In R, adding L after a number explicitly marks it as an integer type instead of the default double (decimal) type.

2. Step 2: Compare with other types

   Without L, numbers are treated as doubles. Adding L ensures the number is stored as an integer.

3. Final Answer:

   It makes the number an integer type. -> Option A

4. Quick Check:

   Number + L = Integer type [OK]

Hint: Remember: number + L means integer in R [OK]

Common Mistakes:

• Thinking L converts to string
• Assuming numbers are integers by default
• Confusing L with a comment

2. Which of the following is the correct way to create an integer value 10 in R?

easy

A. 10.0

B. as.integer("ten")

C. 10L

D. "10"

Solution

1. Step 1: Identify integer syntax in R

   In R, appending L to a number creates an integer literal, so 10L is an integer 10.

2. Step 2: Check other options

   10.0 is a double, "10" is a string, and as.integer("ten") will cause an error because "ten" is not numeric.

3. Final Answer:

   10L -> Option C

4. Quick Check:

   10L creates integer 10 [OK]

Hint: Use L after number for integer, not quotes or decimals [OK]

Common Mistakes:

• Using decimal like 10.0 instead of 10L
• Putting number in quotes to make integer
• Trying to convert non-numeric string to integer

3. What is the output of this R code?

x <- 5L
typeof(x)

medium

A. "double"

B. "integer"

C. "numeric"

D. "character"

Solution

1. Step 1: Understand the variable assignment

   The variable x is assigned 5L, which is an integer literal in R.

2. Step 2: Use typeof() function

   The typeof() function returns the internal type of the object. Since x is an integer, it returns "integer".

3. Final Answer:

   "integer" -> Option B

4. Quick Check:

   typeof(5L) = "integer" [OK]

Hint: typeof(5L) returns "integer" not "double" [OK]

Common Mistakes:

• Assuming 5L is double type
• Confusing typeof() with class()
• Expecting numeric instead of integer

4. Identify the error in this R code:

num <- 7
int_num <- numL

medium

A. Missing L after 7 to make integer

B. Cannot assign numeric to integer variable

C. Syntax error due to missing comma

D. Variable numL is not defined

Solution

1. Step 1: Check variable names

   The code tries to assign numL to int_num, but numL is not defined anywhere.

2. Step 2: Understand the error type

   This causes an error because R cannot find the variable numL. The correct way to make num integer is 7L, but here the error is undefined variable.

3. Final Answer:

   Variable numL is not defined -> Option D

4. Quick Check:

   Undefined variable causes error [OK]

Hint: Check variable names carefully for typos [OK]

Common Mistakes:

• Assuming numL is a valid variable
• Thinking missing L after 7 causes error here
• Ignoring undefined variable errors

5. You have a vector v <- c(1, 2, 3). How do you convert all elements to integers efficiently?

hard

A. v <- as.integer(v)

B. v <- c(1L, 2L, 3L)

C. v <- as.character(v)

D. v <- as.numeric(v)

Solution

1. Step 1: Understand the vector type

   The vector v is numeric (double) by default because numbers have no L suffix.

2. Step 2: Convert vector elements to integer

   Using as.integer(v) converts all elements to integer type efficiently without rewriting the vector manually.

3. Final Answer:

   v <- as.integer(v) -> Option A

4. Quick Check:

   Use as.integer() to convert vector elements [OK]

Hint: Use as.integer() to convert numeric vectors to integer [OK]

Common Mistakes:

• Manually rewriting vector with L suffix
• Using as.character() which converts to strings
• Using as.numeric() which keeps double type