Thanks guys for the reply. Here's what I've worked on, and it seems to work. I will certainly check out those lib. I wonder if the bignum lib can be found in repo for ubuntu; this would be sweet of it does.
Code:
int main()
{
using namespace std;
ifstream ifs;
string temp;
vector<string> string_vec;
vector<int> int_vec;
set<int,greater<int> > set_product;
int product = 0;
ifs.open("problem_8.txt");
while( getline(ifs , temp))
string_vec.push_back(temp);
for(int i = 0 ; i<string_vec.size();++i)
{
temp = *(string_vec.begin()+i);
for(int i = 0 ; i < temp.length() ; i++)
{
// cout << temp[i];
int_vec.push_back(static_cast<int> (temp[i]) - 48 );
}
}
}