Palindrome detector using stacks and queues C++ - c++

Question

I am working on palindrome detector in C++ that reads in a file and marks the lines that are palindromes with the indicator "*". Here's what I have.
PalindromeDetector::PalindromeDetector(const string& iFile, const string& oFile) {
myInFile = iFile;
myOutFile = oFile;
}
void PalindromeDetector::detectPalindrome() {
ifstream fin(myInFile.data());
ofstream fout(myOutFile.data());
string nLine, palLine;
while (getline(fin, nLine)){
if (isPalindrome(nLine)){
fout << nLine << " ***";
} else {
fout << nLine;
}
}
fin.close();
fout.close();
}
bool PalindromeDetector::isPalindrome(const string& str) {
Stack<char> charStack(1);
ArrayQueue<char> charQueue(1);
char ch1, ch2;
for ( unsigned i = 0; i < str.size(); i++){
if (isalnum (str[i])){
tolower(str[i]);
try {
charStack.push(str[i]);
charQueue.append(str[i]);
} catch ( StackException& se ){
charStack.setCapacity(charStack.getCapacity() * 2);
charQueue.setCapacity(charQueue.getCapacity() * 2);
charStack.push(str[i]);
charQueue.append(str[i]);
}
} else {
while ( !charStack.isEmpty() || !charQueue.isEmpty() ){
ch1 = charStack.pop();
ch2 = charQueue.remove();
if ( ch1 != ch2 ){
return false;
}
}
}
}
return true;
}
I'm having 2 problems with this so far:
1. It isn't correctly outputting the file with the "*" at the end of the line; it's doing it at the front for some reason.
2. It only marks the first line in each block of the file, not the lines that are palindromes.
I would really appreciate some help on this.

Answer 1

Why are you making isPalidrome so complicated?
Could be done as thus
bool isPalidrome(const string &s) {
int left = 0;
int right = s.length() - 1;
while (left < right) {
if (s[left] != s[right]) return false;
left++; right--;
}
return true;
}
Of course you might what to add case-insensitivity
EDIT
Using the more silly way of stacks and queues
bool isPalidrome(const string &s) {
// Put everything on both
std::stack<char> lifo;
std::queue<char> fifo;
unsigned int loop;
for (loop = 0; loop < s.length); ++loop) {
lifo.push(s[loop]);
fifo.push(s[loop]);
}
// Note stack and queue the characters are in reverse order from each other
for (loop = 0; loop < s.length); ++loop) {
if (lifo.pop() != fifo.pop()) return false;
}
return true;
}