Longest Substring Without Repeating Characters

LongestSubstringWithoutRepeatingCharacters.c

int lengthOfLongestSubstring(char* s) {
	int r, c, i, j;
	int hash[256] = { 0 };
	unsigned char * us = s;
	if (us[0] == '\0') {
		return 0;
	}
	r = 0;
	i = 0;
	j = 0;
	c = 0;
	while (us[j] != '\0') {
		while (us[j] != '\0' && hash[us[j]] == 0x0) {
			hash[us[j]] = 0x1;
			c++;
			j++;
		}
		r = c > r ? c : r;
		c--;
		hash[us[i]] = 0x0;
		i++;
	}
	return r;
}