Valid Palindrome

[code]class Solution {
public:
    bool isPalindrome(string s) {
        bool indicator = true;

        if(s.size() == 0)
         return indicator;

        string::iterator iter1,iter2;
        iter1 = s.begin();
        iter2 = s.end() - 1;

        while((iter1 != s.end()) && !(isalnum(*iter1)))
                iter1++;

        while((iter2 != s.begin()) && !(isalnum(*iter2)))
                iter2--;

        if(iter1 == s.end())
            return indicator;

        while((iter2 - iter1) > 0) {
            while(!(isalnum(*iter1)))
                iter1++;

            while(!(isalnum(*iter2)))
                iter2--;

            if(isdigit(*iter1)) {
                if(*iter1 - *iter2 != 0) {
                    indicator = false;
                    break;
                }
            }else {
                if(!(*iter1 - *iter2 == 32 || *iter1 - *iter2 == -32 || *iter1 - *iter2 == 0)) {
                    indicator = false;
                    break;
                }

            }
            iter1++;
            iter2--;
        }

        return indicator;

    }
};