Tests for palindromes in C and C++
A special case length &lt; 3 seems like a bug. A string aa is a palindrome, and one could successfully argue that a single-letter string is also a palindrome.
A boolean isPalindrome is redundant, and forces the code to test the effectively same condition twice. An early return is perfectly fine here.
A traditional idiomatic (and arguably more performant) way to iterate forward is *first++. Similarly, an idiom for iterating backwards is *--last (that also avoids subtracting 1 beforehand):

    last = possiblePalindrome.end();
    while (first &lt; last) {
        if (*first++ != *--last) {
            return false;
        }
    }
    return true;

The naming is very inconsistent. I don't see the reason to spell palindrome in 3 different ways. A capitalization in iSPalendrome is also strange.