LeetCode Online Judge 题目C# 练习 - Valid Number

Validate if a given string is numeric
Some examples:
"0" => true
" 0.1 " => true
"abc" => false
"1 a" => false
"2e10" => true
Note: It is intended for the problem statement to be ambiguous. You should gather all requirements up front before implementing one.

        public static bool ValidNumber(string s)
        {
            s = s.Trim();
            int eindex = s.IndexOf('e');

            if (eindex == -1)
                return isValidNumber(s);

            string s1 = s.Substring(0, eindex);
            string s2 = s.Substring(eindex + 1);
            return isValidNumber(s1) && isValidNumber(s2);
        }

        public static bool isValidNumber(string s)
        {
            int dot = 0;
            for (int i = 0; i < s.Length; i++)
            {
                // not valid char?
                if (s[i] != '+' && s[i] != '-' && s[i] != '.' && !(s[i] >= '0' && s[i] <= '9'))
                    return false;

                // '+' or '-' in the middle?
                if (i > 0 && (s[i] == '+' || s[i] == '-'))
                    return false;

                // more than two '.'?
                if (s[i] == '.' && dot > 0)
                    return false;
                // count dot
                else if(s[i] == '.')
                    dot++;
            }

            return true;
        }

代码分析：

　　正如题目所说的，这里充满了讨论的空间，什么是valid number 什么不是，面试官说了算。