using namespace std;
#include <iostream>

const int DIM = 100;
double a[DIM], target; 
int  found, loc, n;

int search(const double a[], int n, double target);
void ReadArray(double [], int&);
void printArray(const double a[], int n);

int main()
{
  ReadArray(a,n);
  do {
    printArray(a,n);
    cout << "Target: ";  
    cin >> target;
    loc = search(a,n,target);
    if (loc>=0) 
      cout << target << " is at a[" << loc << "].\n\n";
    else 
      cout << target << " was not found.\n\n";
  } while (target >= 0.0);
  return 0;
}

//  Binary Search:
int search(const double a[], int n, double target)
{
  bool found=false;
  int location, left = 0, right = n-1;
  while (!found && left <= right) {
    location = (left + right)/2;  
    if (a[location] == target)
      found = true;
    else if (a[location] < target) 
      left = location + 1;
    else 
      right = location - 1;
  }
  return (found ? location : -1);
}

void ReadArray(double a[], int& n)
{
  cout << "Quanti elementi?: ";
        cin >> n;
  for (int i = 0; i < n; i++) {
    cout << "a[" << i << "]: ";  
    cin >> a[i];
  };
}

void printArray(const double a[], int n)
{
   for (int i = 0; i < n; i++)
           cout << '\t' << "a[" << i << "]: " << a[i] << endl;
}