Excel Sheet Column Number(C++)

171.Excel Sheet Column Number

Problem description:

Given a column title as appear in an Excel sheet, return its corresponding column number.

For example:

    A -> 1
    B -> 2
    C -> 3
    ...
    Z -> 26
    AA -> 27
    AB -> 28 

Difficulty:Easy

class Solution {

public:
    int titleToNumber(string s) {
        int num = 0;
int len = s.length();
for (int i = 0;i<len;i++)
{
num = num * 26;
int tmpI = s[i] - '\0' - 64;
num += tmpI;
}
return num;
    }

};

以前项目中，用C#写过一版，现在看到这个题目，Happy地用C++重写一次。