Question
Write a program to generate personalized junk mail. The program takes input both from an input file and from the keyboard. The input file contains the text of a letter, except that the name of the recipient is indicated by the three characters #N#. The program asks the user for a name and then writes the letter to a second file but with the three letters #N# replaced by the name. The three-letter string #N# will occur exactly once in the letter.
Hint : Have your program read from the input file until it encounters the three characters #N#, and have it copy what it reads to the output file as it goes. When it encounters the three letters #N#, it then sends output to the screen asking for the name from the keyboard. You should be able to figure out the rest of the details. Your program should define a function that is called with the input- and output-file streams as arguments. If this is being done as a class assignment, obtain the file names from your instructor.
Harder version: Allow the string #N# to occur any number of times in the file. In this case the name is stored in two string variables. For this version assume that there is a first name and last name but no middle names or initials.
Answer
Complete Program (Harder Version):
#include <iostream>
#include <string>
#include <fstream>
#include <cstdlib>
using namespace std;
void generateJunkMail(ifstream& infile, ofstream& outfile);
int main()
{
string inputFileName;
string outputFileName;
ifstream infile;
ofstream outfile;
cout << "Enter the input file name: ";
cin >> inputFileName;
infile.open(inputFileName);
if (infile.fail())
{
cout << "The input file " << inputFileName
<< " does not exist!" << endl;
exit(1);
}
cout << "Enter the output file name: ";
cin >> outputFileName;
outfile.open(outputFileName);
if (outfile.fail())
{
cout << "The output file " << outputFileName
<< " does not exist!" << endl;
exit(1);
}
generateJunkMail(infile, outfile);
infile.close();
outfile.close();
return 0;
}
void generateJunkMail(ifstream& infile, ofstream& outfile)
{
char ch1, ch2, ch3;
char foundCode = 0;
while (infile.get(ch1))
{
char firstName[21], lastName[21];
if ('#' == ch1)
{
infile.get(ch2);
if ('N' == ch2)
{
infile.get(ch3);
if ('#' == ch3)
{
if (foundCode == 0)
{
foundCode = 1;
cout << "Enter a first and last names: ";
cin >> firstName >> lastName;
outfile << firstName << " " << lastName;
}
else
{
outfile << firstName << " " << lastName;
}
}
else
{
infile.putback(ch3);
}
}
else
{
infile.putback(ch2);
}
}
else
{
outfile << ch1;
}
}
}