Kaelan

Decided to try and cook up a solution. Did some testing, it handled all the test cases I threw at it correctly. It's not exactly a pretty solution, but eh.

#include <list>

inline bool isAlphanumeric(_TCHAR ch) {

    return ((ch >= 'a') && (ch <= 'z') || (ch >= 'A') && (ch <= 'Z') || (ch >= '0') && (ch <= '9'));

}

int isPalindrome(_TCHAR* string) {

    // init

    if (string == 0) return -1;

    _TCHAR *c = string;

    std::list<_TCHAR> stack;

    // build stack

    while (*c != 0)

        stack.push_back(*c++);

    _TCHAR a, b;

    while (stack.size() > 1) {

        // pull the start and end items off the stack

        a = stack.front(); b = stack.back();

        stack.pop_front(); stack.pop_back();

        if (a != b) return 0;

        // they are both equal so just test one

        if (!isAlphanumeric(a)) return 0;

    }

    // if the middle character is not alphanumeric the stack scanning algorithm won't catch it, so check

    if ((stack.size() > 0) && (!isAlphanumeric(stack.back()))) return 0;

    return 1;

}