Validate if a given string is numeric.

Some examples:

"0"=>true
" 0.1 "=>"abc"=>false
"1 a"=>"2e10"=>true

Note:It is intended for the problem statement to be ambiguous. You should gather all requirements up front before implementing one.

Update (2015-02-10):
The signature of theC++function had been updated. If you still see your function signature accepts aconst char *argument,please click the reload buttonto reset your code definition.

1）可以直接的用很多if判断。

2）网上有用有限状态机的。http://www.jb51.cc/article/p-hosklxsd-ve.htmlhttp://www.jb51.cc/article/p-xyiwheub-rn.html

3）正则表达式。

不太懂，mark一下。