Question

write a c++ code to read multiple integers from input.dat until the end of file.

Edit input.dat and put several integers in it. Compile and execute the code then check

output.dat to verify all the integers are in there.

Update the code to check to see if input.dat exists before reading from it. If it

doesn’t exist print an error message (and don’t read!). Compile and execute your code.

Delete input.dat and output.dat and execute – did you see your error message? Is output.dat

there (and empty)? Should it be there at all?

Add code to get the names of both input and output files to the program.

Compile and execute your code. Test it with an input file that does exist. Test it with an

input file that does not exist. Add two small functions to your modified program. One that reads the

number from the input file. One that writes the number to the output file. Write the numbers

formatted as dollar amounts, with a $ and exactly 2 digits to the right of the decimal. Add code to test to see if the input file is empty or not. Print a message if it is and end the program.

Answer 1

Code

#include<iostream>
#include<fstream>
#include<vector>
#include<string>
#include<iomanip>
using namespace std;
//function prototypes
void readFile(ifstream &, vector<double>&);
void writeFile(ofstream &, vector<double>);
int main()
{
   ifstream in;
   string inputFile, outputFile;
   vector<double> values;
   //taking input and output file names
   cout << "Enter input filename: ";
   cin >> inputFile;  
   cout << "Enter output filename: ";
   cin >> outputFile;
   in.open(inputFile);
   if (!in)//checks if file opened or not
   {
       cout << inputFile << " is not found! Exiting program." << endl << endl;
       system("pause");
       return 0;
   }
   if (in.peek() == std::ifstream::traits_type::eof())//checks if file is empty or not
   {
       cout << inputFile << " is empty. Exiting program" << endl << endl;
       system("pause");
       return 0;
   }

   ofstream out(outputFile);
   readFile(in,values);//call the function to read the integer into vector
   writeFile(out, values);//call the function to write to the output file
   in.close();
   out.close();
   system("pause");
   return 0;
}
//function that will read the number and add to the vectors
void readFile(ifstream &in, vector<double>& values)
{
   double val;
   while (!in.eof())
   {
       in >> val;
       values.push_back(val);
   }
}
//function that will write all the number with dollar sign to output file
void writeFile(ofstream &out, vector<double>values)
{
   out << fixed << setprecision(2);
   for (int i = 0; i < values.size(); i++)
       out <<"$" <<values.at(i) << endl;
}

output

where file is not found

when file is empty

when input file has some data

input.dat

output.dat

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