R Program to Check if a String is a Palindrome

Introduction

A palindrome is a word, phrase, number, or other sequence of characters that reads the same forward and backward (ignoring spaces, punctuation, and capitalization). This guide will walk you through writing an R program that checks whether a given string is a palindrome.

Problem Statement

Create an R program that:

• Prompts the user to enter a string.
• Checks if the string is a palindrome.
• Displays a message indicating whether the string is a palindrome or not.

Example:

• Input: "madam"
• Output: "madam is a palindrome"

Solution Steps

1. Read the Input String: Use the readline() function to take the string input from the user.
2. Normalize the String: Convert the string to lowercase and remove any non-alphanumeric characters to ensure that the comparison is case-insensitive and ignores spaces or punctuation.
3. Check if the String is a Palindrome: Reverse the string and compare it to the original normalized string.
4. Display the Result: Use the print() function to display whether the string is a palindrome or not.

R Program

# R Program to Check if a String is a Palindrome
# Author: https://www.javaguides.net/

# Step 1: Read the input string from the user
input_string <- readline(prompt = "Enter a string: ")

# Step 2: Normalize the string
# Convert to lowercase and remove non-alphanumeric characters
normalized_string <- tolower(gsub("[^a-zA-Z0-9]", "", input_string))

# Step 3: Check if the string is a palindrome
is_palindrome <- function(str) {
  return(str == rev(strsplit(str, NULL)[[1]]) %>% paste(collapse = ""))
}

if (is_palindrome(normalized_string)) {
  print(paste("\"", input_string, "\" is a palindrome", sep = ""))
} else {
  print(paste("\"", input_string, "\" is not a palindrome", sep = ""))
}

Explanation

Step 1: Read the Input String

• The readline() function prompts the user to enter a string. The input is read as a character string.

Step 2: Normalize the String

• The tolower() function converts the string to lowercase to ensure case-insensitive comparison.
• The gsub() function removes all non-alphanumeric characters (such as spaces and punctuation) from the string.

Step 3: Check if the String is a Palindrome

• The is_palindrome() function checks if the normalized string is equal to its reverse. The string is split into individual characters, reversed using rev(), and then reassembled using paste().

Step 4: Display the Result

• The program checks the result from the is_palindrome() function and prints whether the input string is a palindrome or not.

Output Example

Example:

Enter a string: madam
[1] "madam is a palindrome"

Example:

Enter a string: hello
[1] "hello is not a palindrome"

Conclusion

This R program demonstrates how to check if a string is a palindrome by normalizing the string and comparing it to its reverse. It covers important concepts such as string manipulation, functions, and conditional statements, making it a practical example for beginners learning R programming.