Binary Search Algorithm Variations and Problems

Binary Search is a simple algorithm but is tricky when it comes to implementing it. The lower and upper bounds have to be set carefully to avoid those silly errors.
I personally prefer the iterative version to avoid unnecessary use of recursive calls.

Below is the standard algorithm

bool search(int x[], int n, int k) {
    int l = 0, r = n-1;
    while (l <= r) {
        int m = (l+r)/2;
        if (x[m] == k) return true;
        if (x[m] < k) l = m+1; else r = m-1;
    }
    return false;
}

Now lets try to find the first element greater than given element

int search(int x[], int n, int k) {
    int l = 0, r = n-1;
    while (l <= r) {
        int m = (l+r)/2;
        if (x[m] < k) l = m+1; 
        else {
              r = m-1;
              index = m;
        }
    }
    return index;
}

i will continue updating this post