Valid Number--LeetCode

 class Solution {
 public:
 bool isNumber(string s) {
     if(s == " ") return false;
     int i = ;
     int j = s.size()-;
     while(s[i] == ' ') ++i;
     while(s[j] == ' ') --j;
     ++j;

     if(s[i] == '+' || s[i] == '-') ++i;

     if(i == j) return false;

     bool numberic = true;
     bool flag = false;

     int k = scanDigits(s,i,j);
     if (k != i)
     {
         flag = true;
     }

     i = k;

     if(i < j){
         if(s[i] == '.'){
             ++i;
             if(i == j && !flag) return false;
             else
             {
                 k = scanDigits(s,i,j);
                 if (k != i)
                 {
                     flag = true;
                 }
                 i = k;
                 if(i < j && (s[i] == 'E'||s[i] == 'e'))
                     numberic = flag && isExponential(s, (++i),j);
             }

         }
         else if(i < j && (s[i] == 'E'||s[i] == 'e'))
             numberic = flag && isExponential(s, ++i,j);
         else numberic = false;
     }

     return numberic && i == j;

 }

 int scanDigits(string str, int i,int j){
     while(i < j && str[i] >= ''&& str[i] <= '') ++i;
     return i;
 }

 bool isExponential(string str, int& i, int j){
     if(i == j) return false;
     if(str[i] == '+' || str[i] == '-') ++i;

     if(i == j) return false;
     i = scanDigits(str,i,j);
     return i==j?true:false;
 }
 };

测试了好多次才过了 太不容易 所以贴个上来做下纪念

".9e1","+.1"  "1."都正确