#include
#include
#include

using namespace std;

bool is_palindrome(string line)
{
deque characters;

// push each alphabetic character onto the deque lowercased
for (string::iterator i = line.begin(); i != line.end(); i++)
if (isalpha(*i))
characters.push_back(tolower(*i));

while (!characters.empty())
{
// take something off the front
char left = characters.front();
characters.pop_front();

// if we’re out of things, then we’re a palindrome because this is
// the odd character that was left over.
if (characters.empty())
return true;

// take something off the end
char right = characters.back();
characters.pop_back();

// if the thing from the front and the thing from the end are the same,
// we still may be a palindrome
if (left != right)
return false;
}

// if we make it here without more stuff on the end, we are a palindrome
return characters.empty();
}

int main()
{
string line;

// read in a line
cout << "Enter a line to check: ";
getline(cin, line);

// so, is it a palindrome?
bool palindrome = is_palindrome(line);

// display different messages depending
if (palindrome)
cout << "Palindrome!" << endl;
else
cout << "Not a palindrome. :(" << endl;

// make this state our UNIX return status, depending
return (int)!palindrome;
}

This could probably be improved by just running a forward and a backward iterator in parallel instead of copying the string into a deque, but this made more sense to me.

Also, ! the if statement when checking for tolower, that way you can put the cout not a palindrome logic in there without an if-else statement, only need an if statement.

This one doesn’t care about the length beyond the fact that the character array is given a limit on length, and calculates it as it inputs instead of needing to input it and then reiterate to calculate the length.

Also I decided to go with pointers over the array notation.

Though this solution could be wrong, I’m only in an intro C++ course and saw this post on reddit.

#include
using namespace std;

int main()
{
// Wouldn’t this be an easier way to input the characters?

const int SIZE = 50;
char* charArray = new char[SIZE];
char* tempStartPointer = charArray;
char* tempEndPointer = charArray;

int length = 0;
char c = cin.get();
while(c != ‘n’ && length < SIZE – 1) // SIZE 1 for null char
{
*(tempEndPointer++) = c;
length++;
c = cin.get();
}

// for debugging give it the extra null char
*tempEndPointer = '';

// move tempEndPointer back one so it is at the end of the string
tempEndPointer–;

while(tempStartPointer < tempEndPointer)
{
if(!isalpha(*tempStartPointer))
{
tempStartPointer++;
continue;
}

if(!isalpha(*tempEndPointer))
{
tempEndPointer–;
continue;
}

if(toupper(*tempStartPointer++) != toupper(*tempEndPointer–))
{
cout << "NOT A PALINDROME";
break;
}
}

cout << "PALINDROME HELL YEAH";

delete[] charArray;

return 0;
}