C++ Primer, Exercise 08-03,08_14,08_15,08_16

#include <iostream>
#include <string>
#include <sstream>
#include <fstream>
#include <vector>
using namespace std;
istream& readall(istream& is)
{
string str;
while(is>>str)
{
cout<<str;
}
is.clear();
cout<<endl;
return is;
}

ifstream& open_file(ifstream& in,const string &file)
{
in.close();
in.clear();
in.open(file.c_str());
return in;
}
void test08_14()
{
string s("006.txt"),outstr;
ifstream is;
open_file(is,s);
while(is>>outstr)
{
cout<<outstr<<endl;
}
}
void test08_15(string line)
{
stringstream strstream(line);
readall(strstream);
}
void test08_16()
{
ifstream in;
string s;
open_file(in,"005.txt");
vector<string> vecline;
while(getline(in,s))
{
vecline.push_back(s);
}
for(vector<string>::iterator iter = vecline.begin();
iter!=vecline.end();iter++)
{
test08_15(*iter);
}
}
int main()
{
test08_14();
test08_15("this is a test line for stringstream");
test08_16();
//readall(cin);
return 0;
}