String Manipulation Functions

Part of the Fundamentals section of Coddy's R journey — lesson 66 of 78.

Now that you know how to split strings into characters, let's explore a few essential functions for working with strings in R. These functions help you measure, combine, and transform text data.

The nchar() function returns the number of characters in a string:

word <- "hello"
print(nchar(word))

Output:

[1] 5

To combine multiple strings into one, use paste(). By default, it separates elements with a space:

result <- paste("Hello", "World")
print(result)

Output:

[1] "Hello World"

Use paste0() when you want no separator between strings:

result <- paste0("Hello", "World")
print(result)

Output:

[1] "HelloWorld"

For case conversion, R provides toupper() and tolower():

print(toupper("hello"))
print(tolower("WORLD"))

Output:

[1] "HELLO"
[1] "world"

These functions become powerful when combined with the iteration techniques you've learned, allowing you to process and transform text character by character or as whole strings.

Challenge

Easy

You will receive two lines of input:

A first name (e.g., john)
A last name (e.g., SMITH)

Perform the following operations:

Convert the first name to uppercase using toupper()
Convert the last name to lowercase using tolower()
Combine them into a full name using paste() (with a space between)
Calculate the total number of characters in the full name (including the space) using nchar()
Create a username by combining the first name and last name with no separator using paste0(), all in lowercase
Print the full name
Print the character count
Print the username

For example, if the inputs are:

alice
WONDER

The output should be:

[1] "ALICE wonder"
[1] 12
[1] "alicewonder"

Explanation: The first name "alice" becomes "ALICE" (uppercase), the last name "WONDER" becomes "wonder" (lowercase). The full name "ALICE wonder" has 12 characters (including the space). The username combines both names in lowercase with no separator: "alicewonder".

Cheat sheet

The nchar() function returns the number of characters in a string:

word <- "hello"
print(nchar(word))  # Output: [1] 5

The paste() function combines multiple strings with a space separator by default:

result <- paste("Hello", "World")
print(result)  # Output: [1] "Hello World"

The paste0() function combines strings with no separator:

result <- paste0("Hello", "World")
print(result)  # Output: [1] "HelloWorld"

The toupper() function converts strings to uppercase, and tolower() converts to lowercase:

print(toupper("hello"))  # Output: [1] "HELLO"
print(tolower("WORLD"))  # Output: [1] "world"

Try it yourself

# Read input
con <- file("stdin", "r")
first_name <- suppressWarnings(readLines(con, n = 1))
last_name <- suppressWarnings(readLines(con, n = 1))
close(con)

# TODO: Write your code below
# 1. Convert first_name to uppercase using toupper()
# 2. Convert last_name to lowercase using tolower()
# 3. Combine them into full_name using paste()
# 4. Calculate character count using nchar()
# 5. Create username using paste0() (all lowercase)

# Output the results
print(full_name)
print(char_count)
print(username)