In the R programming language, you can obtain user input, specify default input values, and manage program output using various functions and techniques. Here are some common methods for handling input and output in R:
1. readline(): You can use the readline() function to prompt the user for input and store the entered text as a character string. For example:
user_input <- readline(“Enter your name: “)
cat(“Hello, “, user_input, “!\n”)
2. read.table() and read.csv(): These functions are typically used to read data from files, but you can also use them to read data from the console if you provide the necessary input interactively.
Default Input:
You can specify default input values in your R script using conditional statements, such as if and else, to check whether user input is provided. If not, you can assign default values.
user_input <- readline(“Enter a number (or press Enter for the default value): “)
if (nzchar(user_input)) {
num <- as.numeric(user_input)
} else {
num <- 42 # Default value
}
cat(“You entered: “, num, “\n”)
Program Output:
1. cat(): The cat() function is commonly used to print output to the console. You can use it to display results, messages, or any other text.
cat(“This is a message.\n”)
2, print(): The print() function is used to display the value of an object, and it is called implicitly when you enter an object’s name at the console prompt.
x <- 10
print(x) # Equivalent to just typing ‘x’ at the console
3. **cat() and paste() with paste0(): You can use these functions to combine text and variable values in output messages.
name <- “John”
age <- 30
cat(“Name: “, name, “, Age: “, age, “\n”)
4. sprintf(): This function is useful for formatting text and numbers in a more controlled way.
name <- “Alice”
age <- 25
message <- sprintf(“Name: %s, Age: %d”, name, age)
cat(message, “\n”)
These are some of the fundamental ways to handle user input and program output in R. Depending on your specific application and requirements, you may use a combination of these techniques to create interactive and informative R scripts or programs.
