Longest palindrome in C++ (readable version)

gistfile1.c++

#include <iostream>
#include <string>
using namespace std;

#define MAX_STR(a, b) (((a.length()) > (b.length())) ? (a) : (b))

string getPalindromeAt(string str, int lower, int upper) {
  for(;lower >= 0 and upper < str.length() and str[lower] == str[upper]
      ;upper++, lower--);
  return str.substr(lower + 1, upper - lower - 1);
}

string getPalindromeAt(int center, string str) {
  string even = getPalindromeAt(str, center, center + 1);
  string odd  = getPalindromeAt(str, center - 1, center + 1);
  return MAX_STR(even, odd);
}

string findLongestPalindrome(string str) {
  string max = "";
  for(int i = 0; i < str.length(); i++) {
    max = MAX_STR(max, getPalindromeAt(i, str));
  }
  return max;
}

int main(void) {
  cout << findLongestPalindrome("ISAAS") << " = SASS"<< endl;
  cout << findLongestPalindrome("a") << " = a" << endl;
  cout << findLongestPalindrome("ab") << " = a" << endl;
  cout << findLongestPalindrome("bba") << " = bb" << endl;
  cout << findLongestPalindrome("abb") << " = bb" <<endl;
  cout << findLongestPalindrome("aba") << " = aba" << endl;
  cout << findLongestPalindrome("Very fast racecar.") << " = racecar" << endl;
  cout << findLongestPalindrome("a bb aba abba abcba cddc cdc dd c") << " = ba abba ab" << endl;
  return 0;
}