[Leetcode] Valid number to confirm whether it is a numeric value

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.

Click to show spoilers.

Update (2014-12-06):
New test cases had been added. Thanks Unfounder ' s contribution.

Confirm that the input string is a numeric value, a series of judgments, mainly some positional judgments:

1. Enter Front space
2. PLUS sign
3. Consecutive values, including '. '
4. Symbol E
5. PLUS sign
6. Consecutive values, not including '. '
7. Subsequent spaces

Follow the rules above.

#include <iostream>using namespacestd;classSolution { Public:    BOOLIsnumber (Const Char*s) {intIDX =0;  for(; s[idx]==' '; idx++); if(s[idx]=='-'|| s[idx]=='+') idx++; intPoint=0, num=0;  for(;(s[idx]>='0'&&s[idx]<='9')|| s[idx]=='.'; idx++) S[idx]=='.'? point++:num++; if(point>1|| num<1)return false; if(s[idx]=='e') {idx++; if(s[idx]=='-'|| s[idx]=='+') idx++; Num=0;  for(; s[idx]>='0'&&s[idx]<='9'; idx++) num++; if(num<1)return false; }         for(; s[idx]==' '; idx++); returns[idx]==' /'; }};intMain () {Chara[]="-e-";    Solution Sol; cout<<sol.isnumber (a) <<Endl; return 0;}

[Leetcode] Valid number to confirm whether it is a numeric value