LeetCode OJ：Compare Version Numbers（比较版本字符串）

Compare two version numbers version1 and version2.
If version1 > version2 return 1, if version1 < version2 return -1, otherwise return 0.

You may assume that the version strings are non-empty and contain only digits and the . character.
The . character does not represent a decimal point and is used to separate number sequences.
For instance, 2.5 is not "two and a half" or "half way to version three", it is the fifth second-level revision of the second first-level revision.

Here is an example of version numbers ordering:

0.1 < 1.1 < 1.2 < 13.37

注意可能会出现前置0的情况，所以分为小数点钱与小数点后转换成数字来判断，代码如下：

 class Solution {
 public:
     int compareVersion(string version1, string version2) {
         int i1, i2;
         int val1, val2;
         for(i1 = , i2 = ; i1 < version1.size() || i2 < version2.size(); ++i1, ++i2){
             val1 = ;
             for(; i1 < version1.size(); ++i1){
                 if(version1[i1] == '.')
                     break;
                 val1 = val1 *  + version1[i1] - '';
             }
             val2 = ;
             for(; i2 < version2.size(); ++i2){
                 if(version2[i2] == '.')
                     break;
                 val2 = val2 *  + version2[i2] - '';
             }
             if(val1 > val2)
                 return ;
             else if(val1 < val2)
                 return -;
         }
         return ;
     }
 };