/*
   Example echoInt3.cpp      shinnerl@ucla.edu   2/5/2002
   -----------------------------------------------------
   Echo all ASCII values of a file's contents to 
   either the screen, or to a user-specified file, if requested
   by an optional command-line argument.

   As before, to avoid an excess of conditional blocks testing 
   where the output should go, we use a pointer to an output stream. 

   We can set this pointer inside a local function, rather
   than in main(), if we pass the pointer to the function
   *by reference.*

   See related example echoInt2.cpp for additional explanation.
*/
#include <iostream>
#include <fstream>
#include <string>
#include <cstdlib>
#include <iomanip>
#include <cassert>
using namespace std;

const int FIELDWIDTH  = 10;
const int INTSPERLINE = 6;
const string sep = "  ";

void getCommandLine( int argc, char* argv[], 
		     ifstream& is, ofstream& os, ostream*& osPtr ){

   if (argc > 1)
      cout << "The input file name is " << argv[1] << "." << endl;
   else{
      cout << "The input file name must be provided as a command-line "
	   << "argument.\n"
	   << "Syntax: echoInt3 <input file> [output file (optional)] " 
	   << endl << endl;
      exit(-1);
   }

 // Open the file and attach the ifstream to it.
   is.open( argv[1] );   // ifstream::open() requires a C-style string.
   if (!is){
     cout << "File not found!" << endl;
     exit(1);
   }

   if (argc > 2){
     os.open( argv[2] );
     assert( os );
     osPtr = &os;
     cout << "The output file name is " << argv[2] << ".\n" << endl;
   }
}

int main(int argc, char* argv[]){

   ifstream userIfs;
   ostream* osPtr = &cout;   // Output to the screen by default.
   ofstream userOfs;
   getCommandLine( argc, argv, userIfs, userOfs, osPtr );

 // Print the ASCII values of the input stream's contents 
 // to the requested output stream.  Using a pointer avoids
 // the need for repeated checks of which ostream is wanted.

   char ch;
   int i = 0;
   *osPtr << "The ASCII values of the characters in this input file are " 
	  << "\ndisplayed below, " << INTSPERLINE << " values per line: " 
	  << endl;
   while (userIfs.get(ch)){
      *osPtr  << setw(FIELDWIDTH) << int(ch) << sep;
      if (!(++i%INTSPERLINE)) 
	 *osPtr  << endl;
   }
   *osPtr   << "The number of characters in this input stream is "
	    << i << ". " << endl << endl;

   return 0;
}

/*  Sample I/O for file "data.dat" containing one line: abcde:

whale.44> echoInt3 data.dat
The input file name is data.dat.
The ASCII values of the characters in this input stream are 
displayed below, 6 values per line: 
	97          98          99         100         101          10  
The number of characters in this input stream is 6. 

whale.45> echoInt3
The input file name must be provided as a command-line argument.
Syntax: echoInt3 <input file> [output file (optional)] 

whale.46> echoInt3 data.dat dataOut.dat
The input file name is data.dat.
The output file name is dataOut.dat.

whale.47> cat dataOut.dat
The ASCII values of the characters in this input stream are 
displayed below, 6 values per line: 
	97          98          99         100         101          10  
The number of characters in this input stream is 6. 
whale.48>
*/