/** This program determines if a string is a palindrome. A palindrome is a string (list of characters) that is read the same forward and backward. */ /** More comments can be found at the end of the code.*/ /** HAPPY LEARNING! */ /*************** CODE ************************/ #include #include using namespace std; bool isPalindrome (string); /* see 1 */ int main(){ string mystr; cout << "Enter a string: "; getline (cin, mystr); /* see 2 */ if (isPalindrome(mystr)) /* see 3 */ cout << mystr << " is a palindrome \n"; else cout << mystr << " is not a palindrome \n"; } bool isPalindrome(string str) { if (str.empty()) /* see 4 */ return true; int i = 0; /* see 5 */ int j = str.length() - 1; while (i < j) { if (str[i++] != str[j--]) /* see 6 */ return false; } return true; } /*************** COMMENTS ********************/ /* 1. Function declaration. A function needs to be declared before being used. The function definition can be found after main() */ /* 2. These three lines of code allow the user to input a string. */ /* 3. If isPalindrome returns true, print "is a palindrome, otherwise print "is not a palindrome" */ /* 4. An empty string is a palindrome by definition, so we return true. */ /* 5. i mark the start point of the string at position 0, and j marks the end of the string at position length-1 */ /* 6. if the first and the last character are not the same then it is not a palindrome, so we return false. * but if they are the same we increase i by 1 and decrease j by 1. This will allow us to compare the next pair of characters namely position 1 with position length-2. * this will continue until a pair does not match of if we are done comparing all pairs. If no mismatch is found we return true since the word must be a palindrome. */

Check if string is a palindrome - using iteration