Array selectionsort issue and output - c++

Question

Hello I am not sure what is wrong with my code.
Selection Sort works but when the program asks the user again to input a name, they don't get the correct person. Can someone help me? I'm not sure what is wrong.
EDIT: The error I am getting now for the second time I ask for input is "Name not found". I don't get why
Image is here:
http://i.imgur.com/2Gkd0gh.pngh
Here is my complete code:
#include <iomanip>
#include <string>
#include <iostream>
#include <fstream>
using namespace std;
// GLOBAL CONSTANTS
const int NUM_NAMES = 20;
// FUNCTION PROTOTYPES
void getNames(ifstream &, string[], int[], int);
int linearSearch(const string[], int, string);
int binarySearch(const string[], int, string);
void selectionSort(string[], int[], int);
void displayData(const string[], const int[], int);
void displaySearch(const string[], const int[], int);
int main()
{
// LOCAL VARIABLES
string names [NUM_NAMES];
int marks [NUM_NAMES];
ifstream inStream; // Input file stream variable
int index = 0;
string searchWho;
// FUNCTION CALL 1
getNames (inStream, names, marks, NUM_NAMES);
cout << endl;
cout << " Students and Marks:" << endl;
cout << " ______________________________" << endl << endl;
// FUNCTION CALL 2: DisplayData
displayData(names, marks, NUM_NAMES);
// OUTPUT - Perform search - USER INPUT
cout << endl;
cout << " Please enter the first and last name of who who want to look up, seperated with a space." << endl << endl;
cout << " "; cin >> searchWho;
cout << endl << endl;
// FUNCTION CALL 3: linearSearch
index = linearSearch (names, NUM_NAMES, searchWho);
// FUNCTION CALL 4: displaySearch
displaySearch(names, marks, index);
// FUNCTION CALL 5: selectionSort
selectionSort (names, marks, NUM_NAMES);
cout << endl;
cout << " Students and Marks:" << endl;
cout << " ______________________________" << endl << endl;
displayData(names, marks, NUM_NAMES);
// OUTPUT - Perform search - USER INPUT
cout << endl;
cout << " Please enter the first and last name of who who want to look up, seperated with a space." << endl << endl;
cout << " "; cin >> searchWho;
cout << endl << endl;
// FUNCTION CALL 4
index = binarySearch (names, NUM_NAMES, searchWho);
displaySearch(names, marks, index);
cout << " "; return 0;
}
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// FUNCTION 1: getNames
// DESCRIPTION: Function opens data file students.txt
// Function reads data from students.txt and stores data
// appropriately according to customerCode and utilityCharge
// in parallel arrays Customer[] and Charge[]
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
void getNames (ifstream &inStream, string names[], int marks[], int numElts)
{
// Open input file
inStream.open ("students.txt");
string studentNames; // Student names - Last name followed by first
int studentMarks = 0; // Student mark for text/exam
// Read in data from students.txt
while (!inStream.eof())
{
for(int count = 0; count < numElts; count ++)
{
inStream >> names[count];
inStream >> marks[count];
}
}
inStream.close();
}
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// FUNCTION: LinearSearch
// DESCRIPTION:
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
int linearSearch (const string names[], int numElts, string who)
{
int index = 0; // Used as a subscript to search array
int position = -1; // To record position of search value
bool found = false; // Flag to indicate if value was found
while (index < numElts && !found)
{
if (names[index] == who) // If the name is found
{
found = true; // Set the flag
position = index; // Record the value's subscript
}
index++; // Go to the next element
}
return position; // Return the position, or -1
}
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// FUNCTION: SelectionSort
// DESCRIPTION:
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
void selectionSort(string names[], int marks[], int numElts)
{
int startScan;
int minIndex;
int startName;
for (startScan = 0; startScan < (numElts - 1); startScan++)
{
startName = startScan;
for (int minIndex = startScan + 1; minIndex < numElts; minIndex++)
{
if (names[minIndex] > names[startName])
{
startName = minIndex;
string tempString = names[startScan];
names[startScan] = names[minIndex];
names[minIndex] = tempString;
// Aligning arrays
int tempInt = marks[startScan];
marks[startScan] = marks[minIndex];
marks[minIndex] = tempInt;
}
}
}
}
int binarySearch(const string names[], int numElts, string who)
{
int first = 0; // First array element
int last = numElts - 1; // Last array element
int middle; // Mid point of search
int position = -1; // Position of search value
bool found = false; // Flag
while (!found && first <= last)
{
middle = (first + last) / 2; // Calculate mid point
if (names[middle] == who) // If value is found at mid
{
found = true;
position = middle;
}
else if (names[middle] > who) // If value is in lower half
{
last = middle - 1;
}
else
{
first = middle + 1; // If value is in upper half
}
}
return position;
}
void displayData(const string names[], const int marks[], int numElts)
{
// OUTPUT
for (int count = 0; count < numElts; count++)
{
cout << " " << left << setw(15) << names[count] << right << setw(15) << marks[count] << endl;
}
}
void displaySearch(const string names[], const int marks[], int index)
{
if (index == -1)
{
cout << " Name not found. Restart the program to search again." << endl << endl;
}
else
{
cout << names[index] << " scored " << marks[index] << " marks." << endl << endl;
}
}

Answer 1

From the shared image http://i.imgur.com/2Gkd0gh.pngh, the array is not properly sorted. For examples,
Allison,Jeff 45
Collins,Bill 80
Allen,Jim 82
As in the code belows:
if (names[minIndex] > names[startName])
{
startName = minIndex;
//...
}
startName means the index of the max name in names array, doesn't it? (the array is descendingly sorted, right?)
So it supposes to be to swap the max name at index startName with the current scanning name at index startScan. Then it should be
startName = startScan;
for (int minIndex = startScan + 1; minIndex < numElts; minIndex++)
{
if (names[minIndex] > names[startName])
{
startName = minIndex;
}
}
string tempString = names[startScan];
names[startScan] = names[startName];
names[startName] = tempString;
// Aligning arrays
int tempInt = marks[startScan];
marks[startScan] = marks[startName];
marks[startName] = tempInt;
And in the binarySearch, it supposes the array is in ascending order.
Therefore, to sort the array in ascending order, you may change
if (names[minIndex] > names[startName])
{
startName = minIndex;
}
to
if (names[minIndex] < names[startName])
{
startName = minIndex;
}