A string is considered a palindrome if it reads the same forward and backward, ignoring spaces, punctuation, and capitalization. To check if a string is a palindrome, first sanitize it by removing unwanted characters and converting it to the same case. Then, compare the sanitized string with its reverse.

To check if a string is a palindrome without using built-in reverse functions, follow these steps:

1. Check for Empty or Null Input
   If the string is empty or null, return true directly or handle it as a special case (empty strings are generally considered palindromes).

2. Sanitize the String
   Ignore spaces, punctuation, and capitalization:

   • Remove all non-alphanumeric characters.

   • Convert all characters to lowercase.

3. Compare Characters from Both Ends
   Use a loop with two pointers:

   • One starting from the beginning.

   • One from the end.
     Compare corresponding characters while moving inward.

4. Return Result
   If all characters match, return true; otherwise, return false.

Pseudocode:

Function isPalindrome(s):
    Initialize an empty string cleanString
    For each character ch in s:
        If ch is alphanumeric:
            Append lowercase of ch to cleanString

    Set reversedString = reverse of cleanString

    If cleanString is equal to reversedString:
        Return true
    Else:
        Return false