#include<iostream>
using namespace std;
int binarysearch(int *a,int key,int n);
int main( )
{
int *arr,n,key;
cout<<"Enter how many elements :";
cin>>n;
arr=new int[n];
cout<<endl<<"Enter elements : ";
for(int i=0;i<n;i++)
cin>>arr[i];
cout<<endl<<"Enter the element to search :";
cin>>key;
int result=binarysearch(arr,key,n);
if(result>=0)
cout<<endl<<"Element found at"<<
result+1<<"position";
else cout<<endl<<"Element not found";
return 0;
}
int binarysearch(int *arr,int key,int n)
{
int low=0,high=n-1;
while(low<=high)
{
int middle=(low+high)/2;
if(key==arr[middle])
return middle;
else if(key>arr[middle])
low=middle+1;
else if(key<arr[middle])
high=middle-1;
}
return -1;
}