Question

 2.12 LAB 2.3: File I/O - CSV update

 This program should

• get names of input and output files from command line (NOT from user input)

• read in integers from a csv (comma-separated values) file into a vector

• compute the integer average of all of the values
  

• convert each value in the vector to the difference between the original value and the average
  

• write the new values into a csv file

Answer 1

Working code implemented in C++ and appropriate comments provided for better understanding:

Source code for main.cpp:

#include
#include
#include

using namespace std;

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

string inputFile;
string outputFile;

if (argc != 3) {
   cout << "Usage: progname inputFile outputFile" << endl;
   return 1;
}

// Assign to inputFile value of 2nd command line argument
inputFile = argv[1];
// Assign to outputFile value of 3rd command line argument
outputFile = argv[2];

// Create input stream and open input csv file.
ifstream inFS(inputFile);

// Verify file opened correctly.
// Output error message and return 1 if file stream did not open correctly.
if (!inFS.is_open()) {
   cout << "Error opening " << inputFile << endl;
   return 1;
}

// Read in integers from input file to vector.
vector intVector;
string inputString;
int inputInt;
bool done = false;
while (!done) {
   inFS >> inputInt;
   intVector.push_back(inputInt);
   if (!inFS.eof()) { // After grabbing int, check for more
       inFS.clear(); // Clear the error state
       char dummyChar;
       inFS >> dummyChar; // Take the comma
   }
   else
   {
       done = true; // we've reached the end, so we're done
   }
}

// Close input stream.
inFS.close();

// Get integer average of all values read in.
int average;
int total = 0;

for (unsigned i = 0; i < intVector.size(); ++i) {
   total = total + intVector.at(i);
}
average = total / intVector.size();

// Convert each value within vector to be the difference between the original value and the average.
for (unsigned i = 0; i < intVector.size(); ++i) {
   intVector.at(i) = intVector.at(i) - average;
}

// Create output stream and open/create output csv file.
ofstream outFS(outputFile);

// Verify file opened or was created correctly.
// Output error message and return 1 if file stream did not open correctly.
if (!outFS.is_open()) {
   cout << "Error opening " << outputFile << endl;
   return 1;
}

// Write converted values into ouptut csv file, each integer separated by a comma.
for (unsigned i = 0; i < intVector.size(); ++i) {
   outFS << intVector.at(i);
   if (i + 1 < intVector.size()) { // if there's more ints to write, put another comma
       outFS << ',';
   }
}

// Close output stream.
outFS.close();

return 0;
}

Sample Output Screenshots:

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