Leetcode Valid Number

(I wrote a water question on leetcode with my teammates)

Portal

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.

Solution:

Test instructions is to judge if a string is not a valid real number (double literal) and actually wants you to implement Istream::istream &operator>> (const double &)(for C + +).

We can certainly hand-code out this function, but it is better to use some flag (member function) dose his own medicine of the IStream class.

Implementation:

1 classSolution {2  Public:3     BOOLIsnumber (strings) {4         intb=0, e=s.size ();5          for(; Isspace (S[b]); b++);6          for(; Isspace (s[e-1]); e--);7         stringT=s.substr (b, E-b);8         if(*t.rbegin ()! ='.'&&!isdigit (*t.rbegin ()))return false;9         if(*t.rbegin () = ='.'&&!isdigit (* (T.rbegin () +1)))return false; Ten StringStream x (t); One         Doubley; AX>>y; -         returnx.eof (); -     } the};

This is probably by far the shortest C + + implementation (if not regular expression) ... Escape

If the range of double in C + + is sufficiently large, it can be achieved even shorter:

1 classSolution {2  Public:3     BOOLIsnumber (strings) {4         intb=0, e=s.size ();5          for(; Isspace (S[b]); b++);6          for(; Isspace (s[e-1]); e--);7StringStream x (s.substr (b, Eb));8         Doubley;9X>>y;Ten         return!x.fail () &&x.eof (); One     } A};

Leetcode Valid Number