string problems

  ofstream a_file ( "example.txt" );
  a_file<<"hello";
  a_file.close();
	
  char *buffer;
  long size;

  ifstream file ("example.txt", ios::in|ios::binary|ios::ate);
  size = file.tellg();
  file.seekg (0, ios::beg);
  buffer = new char [size];
  file.read (buffer, size);
  file.close();

  if (buffer == "hello"){
    cout << "ok\n";
  }
  cout << buffer;

#include <fstream>
#include <iostream>
#include <string>

using namespace std;

int main() {
    ofstream a_file ( "example.txt" );
    //learn to check return values!
    a_file<<"hello";
    a_file.close();

    string buffer, tmp;

    ifstream file ("example.txt", ios::in);
    //learn to check return values!
    while (!file.eof()){
        getline(file, tmp);
        buffer += tmp;
    }
    file.close();

    if (buffer == "hello") {
        cout << "ok\n";
    }

    cout << buffer << endl;

    return 0;
}