CSC133 Intro to CS in C++: Passing Files as Parms

Passing Files as Parameters

//  this program reads pairs of numbers from input file 'numin.dat'
//  for each pair of numbers, it adds the numbers and writes the sum
//  to the output file 'numout.dat'
#include <iostream.h>
#include <fstream.h>
void getInput(ifstream&,int&,int&);
void write(ofstream&,int);
void intro(ofstream&);
int main()
{
   int num1,num2;
   int sum;

//  create file objects and open them
   ifstream infile;
   ofstream outfile;
   infile.open("numin.dat");
   outfile.open("numout.dat");

//  write heading to output file
   intro(outfile);

//  read two numbers at a time, sum them, and output them
//  continue till end of file
   getInput(infile,num1,num2);
   while (infile)
   {
      sum = num1 + num2;
      write(outfile,sum);
	  getInput(infile,num1,num2);
   }
   return 0;
}

//  this function writes a heading to the output file
void intro(ofstream& out)
{
   out << "Program to demonstrate using files with functions\n\n";
}

//  this function reads two numbers from the input file
void getInput(ifstream& in,int& num1,int& num2)
{
   in >> num1 >> num2;
}

//  this function writes the sum to the output file
void write(ofstream& out,int sum)
{
   out << sum << endl;
}

numin.dat

numout.dat

Program to demonstrate using files with functions

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