Question

I have 2 issues with the C++ code below. The biggest concern is that the wrong file name input does not give out the "file cannot be opened!!" message that it is coded to do. What am I missing for this to happen correctly? The second is that the range outputs are right except the last one is bigger than the rest so it will not output 175-200, it outputs 175-199. What can be done about it?

#include <iostream>
#include <fstream>
#include <string>
#include <cstdlib>

using namespace std;

int readTestScores (ifstream &infile, int testScores[]);
void findRanges (int [], int, int[]);
void printResults (int[]);

const int maxStudents = 50;
const int numberOfRanges = 8;
const int rangeSize = 25;

int main()
{
ifstream infile;
string filename;
int count;

int testScores[maxStudents];
int range[numberOfRanges];

cout << "Enter the file name: ";
cin >> filename;
cout << "You entered the file name: " << filename << endl;
cout << endl << endl;

infile.open("testScores.txt");

if (!infile)
{
  cout << filename << "file cannot be opened!!" << endl;
  return 1;
}

count = readTestScores(infile, testScores);

findRanges(testScores, count, range);

printResults(range);

infile.close();

system("pause");

return(0);
}

int readTestScores(ifstream &infile, int testScores[])
{
int score;
int count = 0;

infile >> score;

while (infile && count < maxStudents)
{
  testScores[count] = score;
  
  count++;
  
  infile >> score;
  
}

return count;
}

void findRanges(int testScores[], int count, int range[])
{
int score;

for (int i = 0 ; i < numberOfRanges; i++)
{
  range[i] = 0;
}

for (int i = 0; i < count; i++)
{
  score = testScores[i];
  
  if (score > 0 && score <= 24)
   range[0]++;
  else if (score >= 25 && score <= 49)
   range[1]++;
  else if (score >= 50 && score <= 74)
   range[2]++;
  else if (score >= 75 && score <= 99)
   range[3]++;
  else if (score >= 100 && score <= 124)
   range[4]++;
  else if (score >= 125 && score <= 149)
   range[5]++;
  else if (score >= 150 && score <= 174)
   range[6]++;
  else if (score >= 175 && score <= 200)
   range[7]++;
  else
  {
   cout << endl << "All test scores should be in the 0 to 200 range." << endl;
   exit(1);
  }

}
}

void printResults(int range[])
{
int rangeStart = 0;
int rangeEnd = 24;

cout << "Scores       \tNumber_of_Students" << endl;
for (int i = 0; i < numberOfRanges; i++)
{
  cout << rangeStart << "-" << rangeEnd
    << "\t\t\t" << range[i] << endl;
   
    rangeStart += rangeSize;
    rangeEnd += rangeSize;
   
}
}

Answer 1

Hello, here is the completed code you wanted. Every important statement is explained using comments. Please check and let me know if you have any doubts. Thanks.

modifications in code:

Opening file (line 35) in screen shot

Function printResults (line 144 - 146)

modifications are mentioned in code as comment

CODE

#include <iostream>
#include <fstream>
#include <string>
#include <cstdlib>

using namespace std;

//function prototypes
int readTestScores (ifstream &infile, int testScores[]);
void findRanges (int [], int, int[]);
void printResults (int[]);

//global variables
const int maxStudents = 50;
const int numberOfRanges = 8;
const int rangeSize = 25;

int main()
{
   //variables
   ifstream infile;
   string filename;
   int count;
   int testScores[maxStudents];
   int range[numberOfRanges];

   //prompt for file name
   cout << "Enter the file name (with extension): ";
   cin >> filename;
  
   //printing file name
   cout << "You entered the file name: " << filename << endl;
   cout << endl << endl;
  
   //opening file (code modified)
   infile.open(filename);
  
   //if file not exists
   if (!infile)
   {
       //prints file can't be opened
       cout << filename << "file cannot be opened!!" << endl;
       return 1;
   }
  
   //calling readTestScores
   count = readTestScores(infile, testScores);
  
   //calling findRanges
   findRanges(testScores, count, range);
  
   //calling printResults
   printResults(range);
  
   //closing file
   infile.close();
  
   system("pause");
   return(0);
}

int readTestScores(ifstream &infile, int testScores[])
{
   int score;
   int count = 0;
  
   //reading score from file
   infile >> score;
  
   while (infile && count < maxStudents)
   {
       //storing score into array
       testScores[count] = score;
      
       //incrementing count
       count++;
      
       //reading score from file
       infile >> score;
   }
   //returns count
   return count;
}

void findRanges(int testScores[], int count, int range[])
{
   int score;
  
   //initializing elements in range array as 0
   for (int i = 0 ; i < numberOfRanges; i++)
   {
       range[i] = 0;
   }
  
   //counting ranges
   for (int i = 0; i < count; i++)
   {
       //score from testScores array
       score = testScores[i];
  
       //score between 1 - 24
       if (score > 0 && score <= 24)
           range[0]++;
       //score between 25 - 49
       else if (score >= 25 && score <= 49)
           range[1]++;
       //score between 50 -74
       else if (score >= 50 && score <= 74)
           range[2]++;
       //score between 75 - 99
       else if (score >= 75 && score <= 99)
           range[3]++;
       //score between 100 - 124
       else if (score >= 100 && score <= 124)
           range[4]++;
       //score between 125 - 149
       else if (score >= 125 && score <= 149)
           range[5]++;
       //score between 150 - 174
       else if (score >= 150 && score <= 174)
           range[6]++;
       //score between 175 - 200
       else if (score >= 175 && score <= 200)
           range[7]++;
       //score is out of range
       else
       {
           cout << endl << "All test scores should be in the 0 to 200 range." << endl;
           exit(1);
       }
   }
}

//function modified
void printResults(int range[])
{
   int rangeStart = 0;
   int rangeEnd = 24;
  
   //printing outputs
   cout << "Scores       \tNumber_of_Students" << endl;
   for (int i = 0; i < numberOfRanges; i++)
   {
       //if i is last index (code modified)
       if(i == numberOfRanges - 1)
           rangeEnd++;
      
       //printing counts of range
       cout << rangeStart << "-" << rangeEnd << "\t\t\t" << range[i] << endl;
      
       //incrementing rangeStart and rangeEnd by rangeSize
       rangeStart += rangeSize;
       rangeEnd += rangeSize;
   }
}

OUTPUT

CODE SCREEN SHOT