Leetcode "125" Valid palindrome

Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.

For example,
"A man, a plan, a canal: Panama"is a palindrome.
is not "race a car" a palindrome.

Note:
Are you consider that the string might is empty? This was a good question to ask during a interview.

For the purpose of this problem, we define empty string as valid palindrome.

This is a relatively simple subject, note that using the functions provided by string can be solved quickly. It is worth noting that the case of letters is a problem. directly on the code.

BOOLIspalindrome (strings) {    intLen =s.size (); if(len==0)        return true;  for(intI=0, j=len-1;i<J;) {         while(!isalpha (s[i]) &&!isdigit (s[i]) && i<j) I++;  while(!isalpha (S[j]) &&!isdigit (S[j]) && i<j) J--; if(i==j)return true; if(ToLower (s[i]) = =ToLower (S[j])) {i++; J--; }        Else            return false; }    return true;}

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Leetcode "125" Valid palindrome