Having problems with binary search c++ [closed] - c++

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Im having a problem with a binary search function. It only seems to work when the randomly generated search key is already in the middle position of the array. Ive tried a lot of things but cant seem to figure out why it's doing this.
#include<iostream>
#include<ctime>
using namespace std;
void printarray(int[], int);
void fillarray(int[], int);
void descendingSort(int[], int);
int binarySearch(int[], int, int);
int main()
{
srand((unsigned int)time(0));
bool quit = false;
while (quit == false)
{
int key = rand() % 100 + 1;
const int size = 16;
int mainarray[size] = {};
fillarray(mainarray, size);
printarray(mainarray, size);
descendingSort(mainarray, size);
cout << endl;
cout << "Ordered array after selection sort:" << endl;
printarray(mainarray, size);
cout << endl;
int result = binarySearch(mainarray, size, key);
cout << "Searching for key value " << key << endl;
if (result >= 0)
{
cout << "Key value " << key << " found at position " << result << endl;
}
else
{
cout << "Key value " << key << " not found!" << endl;
}
cout << "Continue (y/n)? :";
char x;
cin >> x;
cout << endl;
if (x == 'y')
quit = false;
if (x == 'n')
quit = true;
}
return 0;
}
void printarray(int array[], int size)
{
for (int i = 0; i < size; i++)
{
cout << array[i] << " ";
}
}
void fillarray(int random[], int size)
{
for (int j = 0; j <= size - 1; j++)
{
random[j] = rand() % 100 + 1;
}
}
void descendingSort(int array[], int size)
{
int max, next;
for (int i = 0; i < size - 1; i++)
{
max = i;
for (int j = i + 1; j < size; j++)
{
if (array[max] < array[j])
max = j;
}
if (max!= i)
{
next = array[i];
array[i] = array[max];
array[max] = next;
}
}
}
int binarySearch(int array[], int size, int key)
{
int low = 0, high = size - 1;
int mid;
while (low <= high)
{
mid = (low + high) / 2;
if (key == array[mid])
{
return mid;
}
else if (key < array[mid])
{
high = mid - 1;
}
else
{
low = mid + 1;
}
}
return -1;
}

Answer 1

Since you are sorting in descending order, your case is backwards.
See code below where I replaces > with <
if (key == array[mid])
{
return mid;
}
else if (key > array[mid])
{
high = mid - 1;
}
else
{
low = mid + 1;
}
By adding some code above the if it allowed me to visualize what was going wrong.
cout << "Searching in: ";
for (int i = low; i < high + 1; i++)
{
cout << array[i] << " ";
}
cout << endl;