Detail Answer In this lab, you will create both recursive and non-recursive func

Question

Detail Answer

In this lab, you will create both recursive and non-recursive function calls to recognize palindromes. A palindrorre is a string that reads the same forward and backward; that is, the letters are the same whether you read them from right to left or from left to right. For example, the one-word string "radar" is a palindrome. More complicated examples include: Straw? No, too stupid a fad. I put soot on warts. Able was I ere I saw Elba Your program takes an input line and decides if it is a palindrome using both recursive and non-recursive functions. Your functions ignore spaces, punctuations, and the difference between upper- and lowercase letters.

Explanation / Answer

#include <iostream>

#include <string>

using namespace std;

bool palindrome_rec(string line)

{

int len = (int)line.length();

if (len == 0)

return true;

if (!isalnum(line[0]))

return palindrome_rec(line.substr(1));

if (!isalnum(line[len-1]))

return palindrome_rec(line.substr(0, len-1));

if (toupper(line[0]) != toupper(line[len-1]))

return false;

return palindrome_rec(line.substr(1, len-2));

}

bool palindrome(string line)

{

int i = 0;

int j = line.length() - 1;

while (i < j)

{

if (!isalnum(line[i])) // ignore spaces or punctualtions

i++;

else if (!isalnum(line[j]))

j--;

else

{

if (toupper(line[i]) != toupper(line[j]))

return false;

i++;

j--;

}

}

return true;

}

int main()

{

string line;

cout << "Enter a line: ";

getline(cin, line);

if (palindrome(line))

cout << "This is palindrome." << endl;

else

cout << "This is NOT palindrome." << endl;

if (palindrome_rec(line))

cout << "This is palindrome(recursive)." << endl;

else

cout << "This is NOT palindrome(recursive)." << endl;

return 0;

}

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