Expert: Joseph Moore - 7/15/2009

Question
Hi there in our previous ? you did give me direction and i did try to compile but when it come to pointers and stings am not full conversant with them because as i had told you earlier am new to programming am just trying to understand every entry you make.
so the ? was this one that i needed you to assist me in getting the codes.


A. Given the following input file called personnel.txt consisting of four columns, employee name, PIN, rate per hour and number of hours worked

 Kamau       A1002342Q 77.32 37
 Njoroge     A2131155Q 88.32 40
 Cheprotich  B3232415W 96.54 40
 Taabu       A4344563W 90.80 35

Write a C++ program that will do the following:
a) Read data from the input file above located in folder    
   c:companypayroll.
b) Calculate the net pay due for each employee
c) print the output so that it is organized as follows

  PIN        Name             Netpay ----------------------------------------------------------
A1002342Q    Kamau             2860.84
A2131155Q    Njoroge           3532.80
B3232415W    Cheprotich        3861.60
A4344563W    Taabu             3178.00  

Answer
OK, here's an implementation of this.  Look it over.  I'm sure you'll have some questions about some of it.  Please, if there is anything that you don't fully understand in the following code, just ask.  I'm happy to explain it.

BEGIN CODE:
-------------------------------------------

#include <string>
using std::string;

#include <vector>
using std::vector;

int countLines(FILE* _pFile, int* _pLongestLine);

class employee
{
public:

   employee()
   {
       mPIN    = "0";
       mName    = "Invalid";
       mRate    = 0.f;
       mHours    = 0;
   }

   void setPIN(const char* _szPIN)
   {
       mPIN = _szPIN;
   }

   const string& getPIN()
   {
       return mPIN;
   }

   void setName(const char* _szName)
   {
       mName = _szName;
   }

   const string& getName()
   {
       return mName;
   }

   void setRate(float _rate)
   {
       mRate = _rate;
   }

   float getRate()
   {
       return mRate;
   }

   void setHours(int _hours)
   {
       mHours = _hours;
   }

   int getHours()
   {
       return mHours;
   }

private:

   string        mPIN;
   string        mName;
   float        mRate;
   int            mHours;
};

employee* createEmployeeFromLine(char* _szLine)
{
   employee* retVal = new employee;
   //Kamau       A1002342Q 77.32 37

   char delims[] = " \t";

   char* szOut = strtok(_szLine, delims);
   if (szOut)
   {
       retVal->setName(szOut);
   }
   else
   {
       delete retVal;
       return NULL;
   }

   szOut = strtok(NULL, delims);
   if (szOut)
   {
       retVal->setPIN(szOut);
   }
   else
   {
       delete retVal;
       return NULL;
   }

   szOut = strtok(NULL, delims);
   if (szOut)
   {
       retVal->setRate((float)atof(szOut));
   }
   else
   {
       delete retVal;
       return NULL;
   }

   szOut = strtok(NULL, delims);
   if (szOut)
   {
       retVal->setHours(atoi(szOut));
   }
   else
   {
       delete retVal;
       return NULL;
   }

   return retVal;
}

int main()
{
   FILE* pFile = fopen("personnel.txt", "rt");
   int nLongestLine;
   int nLines = countLines(pFile, &nLongestLine);

   char* szLineStorage = new char[nLongestLine + 1];

   vector<employee*> employeeVec;

   while (fgets(szLineStorage, nLongestLine + 1, pFile))
   {
       employee* pEmp = createEmployeeFromLine(szLineStorage);
       if (pEmp)
           employeeVec.push_back(pEmp);
   }

   printf("PIN\t\tName\t\tPay\n");
   printf("----------------------------------------\n");
   for (int i = 0; i < (int)employeeVec.size(); ++i)
   {
       printf("%s\t%s\t%.2f\n", employeeVec[i]->getPIN().c_str(), employeeVec[i]->getName().c_str(), employeeVec[i]->getRate() * employeeVec[i]->getHours());
   }
}

// This is a utility function that counts the number of lines in a file as well as
// the length of the longest line.
int countLines(FILE* _pFile, int* _pLongestLine)
{
   // Storage for each character in the file, with previous initialized to \n
   // to prevent empty files from ruining this algorithm.
   char currChar;
   char prevChar = '\n';

   // Number of lines
   int numLines = 0;

   // Tracks the current and longest line lengths
   int curLineLength = 0;
   int longestLine = 0;

   // Keeps file position kosher
   long curFilePos = 0;

   // Make sure the user gave us a file
   if (!_pFile)
       return 0;

   // Store the current file position
   curFilePos = ftell(_pFile);

   // Set the file pointer to the beginning of the file
   fseek(_pFile, 0, SEEK_SET);

   // Go through every character in the file.
   while ((currChar = fgetc(_pFile)) != EOF)
   {
       // Find newline characters
       if (currChar == '\n')
       {
           // Increment number of lines.
           ++numLines;

           // Test for a new longest line
           if (curLineLength > longestLine)
               longestLine = curLineLength;

           // Reset current line length
           curLineLength = 0;
       }

       // Keep a copy to later test whether...
       prevChar = currChar;
       ++curLineLength;
   }

   // Test for a new longest line
   if (curLineLength > longestLine)
       longestLine = curLineLength;

   // If the last line did not end in a newline, then we need to add one more
   // line to the total.
   if (prevChar != '\n')
   {
       ++numLines;
   }

   // Return to the starting file position.
   fseek(_pFile, curFilePos, SEEK_SET);

   // If the user wants it, store the longest line length
   if (_pLongestLine)
       *_pLongestLine = longestLine;

   // Return the counted number of lines
   return numLines;
}

-------------------------------------------
END CODE