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// FILE: search.cxx
// Demonstration program for the binary search function
#include <cstdlib> // Provides EXIT_SUCCESS, size_t
#include <iostream> // Provides cin, cout
using namespace std;
// PROTOTYPE for function used in demonstration program:
void search(
const int a[ ],
size_t first,
size_t size,
int target,
bool& found,
size_t& location
);
int main( )
{
const size_t MANY = 10;
int fibonacci[MANY] = { 1, 2, 3, 5, 8, 13, 21, 34, 55, 89 };
int target;
bool found;
size_t location;
do
{
cout << "Please type an integer from 0 to 100: ";
cin >> target;
}
while ((target < 0) || (target > 100));
search(fibonacci, 0, MANY, target, found, location);
if (found)
cout << target << " is a Fibonacci number at ["
<< location << "] in my array." << endl;
else
cout << target << " is not a Fibonacci number." << endl;
return EXIT_SUCCESS;
}
void search(
const int a[ ],
size_t first,
size_t size,
int target,
bool& found,
size_t& location
)
// Precondition: The array segment starting at a[first] and containing size
// elements is sorted from smallest to largest.
// Postcondition: The array segment starting at a[first] and containing size
// elements has been searched for the target. If the target was present, then
// found is true, and location is set so that target == a[location];
// Otherwise, found is set to false.
// Library facilities used: stdlib.h (provides size_t).
{
size_t middle;
if (size == 0)
found = false;
else
{
middle = first + size/2;
if (target == a[middle])
{
location = middle;
found = true;
}
else if (target < a[middle])
// The target is less than a[middle], so search before the middle
search(a, first, size/2, target, found, location);
else
// The target must be greater than a[middle], so search after the middle
search(a, middle+1, (size-1)/2, target, found, location);
}
}
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