Longest Substring Without Repeating Characters

longestsubstring.c

int lengthOfLongestSubstring(char* s) {
    int len = strlen(s);
    int i=0,count=0,max=0;
    for(i=0;i<len;i++)
    {
        int arr[256]={0};
        count=0;
        int j=0;
        for(j=i;j<len;j++)
        {
            int k = s[j]-' ';
            if(arr[k] == 0)
            {
                arr[k] +=1;
                count++;
            }
            else
                break;
        }
        if(count>max)
            max = count;
        if(max == len)
            break;
    }
    return max;
}