//
// Program name:  binsearch
// Author:  B. Massingill 
//
// Purpose:  
//	binsearch function implements binary search algorithm for
//		searching for an element of an array
//	main program tests function
//
#include <iostream.h>
#include <fstream.h>
#include <stdlib.h>

// code for binary search function is in binsearch.h
#include "binsearch.h"

// code for sort function is in selectionSort.h
#include "selectionSort.h"

// ---- function prototypes (see below for comments) ----

int readFileIntoArray(const char fileName[], int a[], 
	const int arrayLength);
void displayArray(const int a[], const int n);
void searchArray(const int a[], const int n);

// ---- main program ----

int main(int argc, char *argv[])
{
	const int MaxArrayLength = 100;
	int a[MaxArrayLength];
	int arrayLength;

	char prompt[] = "Enter D to display array, "
			"S to search, "
			"Q to quit:\n";
	char cmd;

	if (argc < 2)
	{
		cerr << "Must supply filename as command-line argument"
			<< endl;
		exit(1);
	}

	arrayLength = readFileIntoArray(argv[1], a, MaxArrayLength);
	selectionSort(a, arrayLength);

	cout << prompt;
	while ((cin >> cmd) && (cmd != 'Q'))
	{
		if (cmd == 'D')
			displayArray(a, arrayLength);
		else if (cmd == 'S')
			searchArray(a, arrayLength);
		else
			cerr << "Invalid response\n";
		cout << prompt;
	}
	return 0 ;
}

// ---- supporting functions ----

// precondition:
//	fileName is a null-terminated string representing a filename;
//		the file contains integers
//	arrayLength is the length of array a
// postcondition:
//	if the file exists, up to arrayLength integers have been read
//		into a; the return value is the number of integers
//		read
//	otherwise an error message is printed and the program is
//		terminated
int readFileIntoArray(const char fileName[], int a[], 
	const int arrayLength)
{
	ifstream inS;
	inS.open(fileName);
	if (inS.fail())
	{
		cerr << "Unable to open file " << fileName << endl;
		exit(1);
	}

	int count = 0;
	while ((count < arrayLength) && (inS >> a[count]))
		count++;
	inS.close();
	return count;
}

// precondition:
//	n is the size of a
// postcondition:
//	a[0] .. a[n-1] have been printed 
void displayArray(const int a[], const int n)
{
	cout << "Array elements:\n";
	for (int i = 0; i < n; i++)
		cout << "  " << a[i] << endl;
	return;
}

// precondition:
//	n is the size of a
// postcondition:
//	user has prompted for a search value x
//	if x is found in a, its index is printed; otherwise a "not
//		found" message is printed
void searchArray(const int a[], const int n)
{
	int x;
	cout << "Enter element to search for:\n";
	cin >> x;
	int index = binsearch(a, 0, n-1, x);
	if (index == -1)
		cout << "Not found\n";
	else
		cout << "Found at position " << index << endl;
	return;
}