(in c++, without using #include <iostream.h> or <stdio.h>) Write a recursive fun

Question

(in c++, without using #include <iostream.h> or <stdio.h>)

Write a recursive function that returns true if an input string is a palindrome and false if it is not. You can do this by checking if the first character equals the last character, and if so, make a recursive call with the input string minus the first and last characters. You will have to define a suitable stopping condition. Then write a program that takes in a string as user input, then calls the above function and outputs the result. Input string may have characters and numbers. Ignore case when comparing two chracters.

The program should print a string of text to the terminal before getting the inputs from the user. A session should look like one of the following examples (including whitespace and formatting):

The strings printed by the program should include a newline at the end, but no other trailing whitespace (whitespace at the end of the line).

Explanation / Answer

#include<iostream>
#include<string>
#include <assert.h>

using namespace std;

bool is_palindrome(string);

int main(void) {

   cout << "Starting tests..." << endl;

   const int num_tests = 5;

   string strings[num_tests] = {
       "aibohphobia", "detartrated", "aba", "abba", "wassamassaw"
   };

   string not_strings[num_tests] = {
       "ab", "abc", "abcbba", "redivide", "ccccdecccc"
   };

   for (int i = 0; i < num_tests; i++) {

       assert (is_palindrome(strings[i]));
       assert(!is_palindrome(not_strings[i]));

       cout << strings[i] << (is_palindrome(strings[i])
               ? " is a palindrome"
               : " is not a palindrome" )
           << endl;

       cout << not_strings[i] << (is_palindrome(not_strings[i])
               ? " is a palindrome"
               : " is not a palindrome" )
           << endl;
   }
   cout << "All tests passed." << endl;

   string user_input;
   cout << "Enter string to recursively check for palindrome-ness" << endl;
   cin >> user_input;

   cout << (is_palindrome(user_input)
           ? "Word is a palindrome"
           : "Word is not a palindrome" )
       << endl;

   return 0;
}

bool is_palindrome(string s) {

   if (s.size() <= 1)
       return true;
   if (s.front() != s.back()) {
       return false;
   } else {
       return true && is_palindrome(s.substr(1, s.size() - 2));
   }
}

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