String Operations

String Functions

R has many built-in string manipulation functions:

Length and Case

cat(nchar("hello"), "\n")       # 5
cat(toupper("hello"), "\n")     # HELLO
cat(tolower("HELLO"), "\n")     # hello

Concatenation

cat(paste("hello", "world"), "\n")       # hello world
cat(paste0("hello", "world"), "\n")      # helloworld
cat(paste("a", "b", "c", sep = "-"), "\n") # a-b-c

Substring

x <- "Hello, World!"
cat(substring(x, 1, 5), "\n")  # Hello
cat(substring(x, 8), "\n")     # World!

Search and Replace

x <- "Hello, World!"
cat(gsub("World", "R", x), "\n")       # Hello, R!
cat(grepl("World", x), "\n")           # TRUE

gsub() replaces all matches. sub() replaces only the first match. grepl() returns TRUE or FALSE.

Splitting Strings

parts <- strsplit("a,b,c", ",")[[1]]
cat(parts, "\n")  # a b c

Note: strsplit() returns a list, so use [[1]] to get the character vector.

Formatting

cat(sprintf("Name: %s, Age: %d", "Alice", 30), "\n")
cat(sprintf("Pi is %.2f", 3.14159), "\n")

Your Task

Take the string "hello, world", convert it to uppercase, replace "WORLD" with "R", and print the result.