Help...Binary Search not working

[allendks45]

Having a little trouble with current project. I've read a file that contains first + last names into an array, sorted it with a function and displayed it to screen sorted (this isn't part of the assignment but I wanted to verify the function worked--and it does). I've also called the search function but the name is not being displayed. When I run the program it outputs "is my friend" but not the friends name first. It is also supposed to prompt to enter name again or END to quit. Looking for just a bit of help on this. Spent over 12 hours over 2-days on this. This is my current code.

Thanks for any comments.

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

using namespace std;

//function Prototypes
void nameSort(string friendArray[], int ARRAY_SIZE);
//function to display names from file
void displayNames(string friendArray[], int counter);
//function to binary search for name in file/array 
//How do i return a string?? I got the following code from web searches
int searchName(string friendArray[], int ARRAY_SIZE, string result);

int main()
{
	const int ARRAY_SIZE = 200; //declare array size
	string friendArray[ARRAY_SIZE];//array of 200 strings
	ifstream fileIn; //create file object
	
	int counter = 0;
	string choice;
	string result; //variable to hold the search result

	fileIn.open("myFriends.dat");//open the file
	if(fileIn.fail())//test to see if file opened
	{
		cout<<"Check to see if file is in same directory ";
		cout<<"as the .cpp file."<<endl;
	}
	
	while(getline(fileIn, friendArray[counter]))
	{
		counter++;
	}
	//call function to sort array
	nameSort(friendArray, ARRAY_SIZE);
	//display sorted names to screen with function
	displayNames(friendArray, ARRAY_SIZE);
	//call to search function
	searchName(friendArray, ARRAY_SIZE, result);
	cout<<friendArray[counter]<<" is my friend."<<endl;
		
system("Pause");
return 0;
}

//sort function
void  nameSort(string friendArray[], const int ARRAY_SIZE)
{
	bool swap;
	string temp;

	do
	{
		swap = false; //set flag to false
			for(int counter = 0; counter < (ARRAY_SIZE - 1); counter++)
			{
				if(friendArray[counter] > friendArray[counter + 1])
				{
					temp = friendArray[counter];
					friendArray[counter] = friendArray[counter + 1];
					friendArray[counter + 1] = temp;
					swap = true;
				}
			}//close for loop
	}while(swap);
}//end of function

//display names function

void displayNames(string friendArray[], const int ARRAY_SIZE)
{
	for(int index = 0; index < ARRAY_SIZE; index++)
		cout<<friendArray[index]<<endl;
}

//binary search function
int searchName(string friendArray[], const int ARRAY_SIZE, string result)
{
	int first = 0;
	int last = (ARRAY_SIZE - 1);
	int middle;
	int position = -1;
	string name;
	bool found = false;
	
	cout<<"Please enter a name or END to quit.";
	cin>>name;
	
			while(!found && first <= last && name != "END")
			{
				middle = (first + last) / 2;

				if(friendArray[middle] == result)
				{
					found = true;
					position = middle;
				}
				else if(friendArray[middle] > result)
					last = (middle - 1);
				else 
					first = (middle + 1);
			}
			return position;
		}

[coder777]

on line 42: you use counter to print the name, which is guaranteed to be empty due to line 32. Use the returned index of searchName()

on line 23: it's a misnomer. It's not the search result. Instead it's the name you search for. Currently it's always empty. You might want a cin from the user.

[allendks45]

So I should be using friendArray[position] where position will return the result of the search function?

I'm wondering if I need the statements on line 23 at all. The function is prompting to enter a name and has a variable to hold the name. Could you elaborate on whether this is correct or not from reading my code?

[coder777]

So I should be using friendArray[position] where position will return the result of the search function?

Yes, like so:

	int position = searchName(friendArray, ARRAY_SIZE, result);
	if(position < 0) // Note: -1 must be taken into account
	  cout<<"not found"<<endl;
	else
	  cout<<friendArray[position]<<" is my friend."<<endl;

I'm wondering if I need the statements on line 23 at all.

The way you code it you indeed don't need it (it does not get a value anywhere). Remove it from line 79 and 13.