c++ - Extraction operator causing my program to exit? -

i'm usual lurker first post! understand guys detail best. appreciate whatever input has.

i working on overloading extraction operator object dynamic array of digits. console input have leading white space, int, after. need ignore white space, extract int, , leave rest alone. easy right?

here example of code found online:

    istream & operator >> (istream &m, myint & p) {     int x = 0;     p.currentlength = 0;     while ((m.peek() == '\n') || (m.peek() == '\0') ||            (m.peek() == '\t') || (m.peek() == ' '))     {         m.get();     }         while ((m.peek() >= '0') && (m.peek() <= '9'))     {         if (p.currentlength >= p.maxsize)         {             p.grow();         }         m >> p.thenumber[x];         x++;         p.currentlength++;     }     m.get();     // reverse order (i.e. - 123 321)     char * temp = new char[p.maxsize];         (int y = 0; y < p.currentlength; y++)     {         temp[y] = p.thenumber[p.currentlength - 1 - y];     }        delete [] p.thenumber;     p.thenumber = temp;      return m; } 

now, understand method may work, me, seems extremmeelly inefficient method. trillion digit number, grow() reallocate array trillion times! perhaps not bad think is?

my current method has been using seekg() , peek() , get(). so:

    istream& operator >> (istream& is, myint& z) {     int = 0, j = 0;     // check if next char white     while (is.peek() == 38)     {         j++;         is.seekg(j); // skip if white     }     while (isdigit(is.peek()))     {         i++;         is.seekg(j + i);         if (!is.peek())         {             is.clear();             break;         }     }     is.seekg(j);     z.length = i;      z.digits = new int[i + 1];     (i = 0; < z.length; i++)     {         z.digits[i] = c2i(is.get());     }     return is; } 

also, here main:

  int main() {     myint b;     cout << "\n\nchange b num? ---> ";     cin >> b;     cout << "b now: " << b;      char c;     cout << "\n\n\n\n\nenter char exit :   ";     cin >> c;     return 0; } 

for life of me can not find causing program exit. last output seems say, 'b now: -1'

i believe means << b failed. have b initialized 0 currently, , rest of code has presented no other issues. it's private member data include pointer , length (num of digits). c2i() function converts '0' through '9' 0 through 9.

a big issue me new parsing, don't have eloquent ways test this, or other ideas.

again appreciate guys do. have learned great deal browsing here!