[Valmont]

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

using std::cin;
using std::cout;
using std::string;
using std::ifstream;
using std::endl;
using std::getline;

int main(int argc, char *argv[])
{
   ifstream theFile;
   string theFileName;

   while(1)
   {
      cout<<"\t\t\tEnter the option:"<<endl;
      cout<<"\t\t\t1 = Lab 1.cpp"<<endl;
      cout<<"\t\t\t2 = Lab 2.cpp"<<endl;
      cout<<"\t\t\t3 = Lab 3.cpp"<<endl;
      cout<<"\t\t\t4 = Lab 4.cpp"<<endl;
      cout<<"\t\t\tCTRL+Z/D = quit."<<endl;

      getline(cin, theFileName);
      
      //User wants to quit?
      if( cin.eof() )
      {
         //User wants to quit. Get out of the while-loop.
         break;
      }
      
      //Assuming files are named like: Lab_1.cpp, Lab_2.cpp etcetera.
      theFileName.insert(0, "Lab_");
      theFileName += ".cpp";
      
      theFile.open( theFileName.c_str() );
      
      if( !theFile )
      {
         cout<<endl<<"ERROR!"<<endl;
         cout<<"Reason: could not open the file."<<endl;
         cout<<"Make sure your entry is valid."<<endl<<endl;
         theFile.close();
         theFile.clear();
      }
      
      if( theFile.is_open() )
      {
         cout<<"*** File starts below ***"<<endl<<endl;
         cout<<theFile.rdbuf();
         cout<<endl<<"*** File ended ***"<<endl<<endl;
         theFile.close();
      }
   }
   
   return 0;
}