Longest palindrome substring

/***Compute the longest palindrome substring ***/

#include <iostream>

#include <string>

using namespace std;

bool isPalindrom(string str, int start, int end) {

       if (start == end || start > end) return true;

       while (start != end && start < end)

       {

              if (str[start] != str[end]) return false;

              else {

                     start += 1;

                     end -= 1;

              }

       }

       return true;

}

string chk_longPalindrom(string str, int start, int chklen) {

       string outstr;

       int st;

      

       while (chklen != 0)

       {

              st = start;

              for(unsigned int i = 0; i < str.size()-chklen+1; i++) {

                     if (isPalindrom(str, st, st+chklen-1))

                     {

                           outstr.assign(str.begin()+st, str.begin()+st+chklen);

                           return outstr;

                     }

                     st++;

              }

              chklen–;

       }

       return “”;

}

void main() {

       string str = “FourscoreandsevenyearsagoourfaathersbroughtforthonthiscontainentanewnationconceivedinzLibertyanddedicatedtothepropositionthatallmenarecreatedequalNowweareengagedinagreahtcivilwartestingwhetherthatnaptionoranynartionsoconceivedandsodedicatedcanlongendureWeareqmetonagreatbattlefiemldoftzhatwarWehavecometodedicpateaportionofthatfieldasafinalrestingplaceforthosewhoheregavetheirlivesthatthatnationmightliveItisaltogetherfangandproperthatweshoulddothisButinalargersensewecannotdedicatewecannotconsecratewecannothallowthisgroundThebravelmenlivinganddeadwhostruggledherehaveconsecrateditfaraboveourpoorponwertoaddordetractTgheworldadswfilllittlenotlenorlongrememberwhatwesayherebutitcanneverforgetwhattheydidhereItisforusthelivingrathertobededicatedheretotheulnfinishedworkwhichtheywhofoughtherehavethusfarsonoblyadvancedItisratherforustobeherededicatedtothegreattdafskremainingbeforeusthatfromthesehonoreddeadwetakeincreaseddevotiontothatcauseforwhichtheygavethelastpfullmeasureofdevotionthatweherehighlyresolvethatthesedeadshallnothavediedinvainthatthisnationunsderGodshallhaveanewbirthoffreedomandthatgovernmentofthepeoplebythepeopleforthepeopleshallnotperishfromtheearth”;

       string longsub = chk_longPalindrom(str, 0, str.size());

       cout<<“Long sub string is [ “<<longsub<<” ]”<<endl;

}