[Leetcode] Valid number

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.

Update (2015-02-10):
The signature of the C++ function had been updated. If you still see your function signature accepts a const char * argument, please click on the reload button to reset your cod E definition.

Hide TagsMath String

Idea: Divided into 3 end, before the decimal point, after the decimal point, after E, marked 1 2 3 segment, 1 and 3 segments can have a sign, 1 and 2 can have any 1 segment is empty, but not all empty

As a whole, it's a lot of detail to think about.

Tesecase

intMain () {solution SL;#if1cout<< Sl.isnumber ("0") <<Endl; cout<< Sl.isnumber ("1") <<Endl; cout<< Sl.isnumber ("1.") <<Endl; cout<< Sl.isnumber (". 1") <<Endl; cout<< Sl.isnumber (". ") <<Endl; cout<< Sl.isnumber ("0.1") <<Endl; cout<< Sl.isnumber ("ABC") <<Endl; cout<< Sl.isnumber ("1 A") <<Endl; cout<< Sl.isnumber ("2.223e10") <<Endl; cout<< Sl.isnumber ("005047e+6") <<Endl; cout<< Sl.isnumber ("+++") <<Endl; cout<< Sl.isnumber ("4e+") <<Endl; cout<< Sl.isnumber (". -4") <<Endl;#endifcout<< Sl.isnumber ("+.8") <<Endl; return 0;}

The last Code

classSolution {enumAllow_pos_neg {allow_none, Allow_pos, Allow_neg, allow_all};  Public:        BOOLIsint (stringSenumAllow_pos_neg allow = Allow_none,BOOLAllowEmpty =false) {size_t n=s.size (); cout<<"s:\t"<< s <<Endl; intStart =0; if(Allow = =Allow_pos) {                if(s[0] =='+') {Start++; }            }            Else if(Allow = =Allow_neg) {                if(s[0] =='-') {Start++; }            }            Else if(Allow = =Allow_all) {                if(s[0] =='+'|| s[0] =='-') {Start++; }            }            Else //Allow_none                ; if(Start = =N) {if(AllowEmpty = =true)                    return true; Else                    return false; }             for(inti = start; I < n; i++)            {                if(S[i] >='0'&& S[i] <='9')                    ; Else                    return false; }            return true; }        BOOLIsnumber (strings) {size_t n=s.size (); if(n = =0)                return false; intStart =0, end = n1; //Skip Space             while(Start < n && S[start] = =' ') {Start++; }            //Skip '-'//if (s[start] = = '-' | | s[start] = = ' + ')//start + +;            if(Start = =N)return false; //Skip Space             while(S[end] = =' ') {End-- ; }            stringNewstr = S.substr (start, End-start +1); size_t Founde= Newstr.find ('e'); //cout << "newstr\t" << newstr << Endl; //cout << "founde\t" << founde<< Endl;            if(Founde! =string:: NPOs)//find ' e '            {                if(Founde = =0|| Founde = = Newstr.size ()-1)                    return false; size_t Foundpoint= Newstr.find ('.'); //cout << "foundpoint\t" << foundpoint << Endl;                if(Foundpoint! =string:: NPOs)//find '. '                {                    if(Foundpoint >=Founde)return false; if(Foundpoint = =0)//ex ". 1e34"                        returnIsint (Newstr.substr (foundpoint+1, founde-foundpoint-1), Allow_none)&& Isint (Newstr.substr (founde+1), Allow_all); if(Foundpoint = = founde-1)//ex "3.e40"                        returnIsint (Newstr.substr (0, Foundpoint), Allow_all)&& Isint (Newstr.substr (founde+1), Allow_all); returnIsint (Newstr.substr (0, Foundpoint), Allow_all,true)                        && Isint (Newstr.substr (foundpoint+1, founde-foundpoint-1), Allow_none)&& Isint (Newstr.substr (founde+1), Allow_all); }                Else                    returnIsint (Newstr.substr (0, Founde), Allow_all)&& Isint (Newstr.substr (founde+1), Allow_all); }            Else{size_t Foundpoint= Newstr.find ('.'); //cout << "foundpoint\t" << foundpoint << Endl;                if(Foundpoint! =string:: NPOs)//find '. '                {                    if(Foundpoint = =0)                        returnIsint (Newstr.substr (foundpoint+1), Allow_none); Else if(Foundpoint = = Newstr.size ()-1)                        returnIsint (Newstr.substr (0, Foundpoint), Allow_all); Else                        returnIsint (Newstr.substr (0, Foundpoint), Allow_all,true)                            && Isint (Newstr.substr (foundpoint+1), Allow_none); }                Else                    returnisint (Newstr, Allow_all); }        }};

[Leetcode] Valid number