leetcode - Longest Palindromic Substring

class Solution {
public:
    string longestPalindrome(string s) {
        string res;
        int posSubStrBegin=0, posSubStrEnd=0;
        int posTemp = 0;
        int subStrLength = 1;
        int subStrL;
        while(posTemp != s.length()-1 ){
            int posTempHead, posTempTail;
            if(s[posTemp] == s[posTemp+1]){
                posTempHead = posTemp;
                posTempTail = posTemp+1;
                subStrL = 0;
                while(posTempHead >= 0 && posTempTail <= s.length()-1 
                        && s[posTempHead] == s[posTempTail] ){
                    posTempHead--;
                    posTempTail++;
                    subStrL+=2;
                } 
                if(subStrL>subStrLength){
                    posSubStrBegin = posTempHead+1;
                    posSubStrEnd = posTempTail-1;
                    subStrLength = subStrL;
                }
            }
           
            if(posTemp != 0 && s[posTemp-1] == s[posTemp+1]){
                posTempHead = posTemp-1;
                posTempTail = posTemp+1;
                subStrL = 1;
                while(posTempHead >= 0 && posTempTail <= s.length()-1 
                        && s[posTempHead] == s[posTempTail] ){
                    posTempHead--;
                    posTempTail++;
                    subStrL+=2;
                }
                if(subStrL>subStrLength){
                    posSubStrBegin = posTempHead+1;
                    posSubStrEnd = posTempTail-1;
                    subStrLength = subStrL;
                }
            }
           
            posTemp++;
            
        }
        res.assign(s, posSubStrBegin, subStrLength);
        return res;
    }
};