Add Binary Search

Binary Search.cpp

@@ -0,0 +1,34 @@
+#include <iostream>
+using namespace std;
+int binary_search(int a[],int l,int r,int key){
+	while(l<=r){
+		int m = l+(r-l)/2;
+		if(key==a[m])
+			return m;
+		else if(key<a[m])
+			r = m-1;
+		else
+			l = m+1;
+	}
+	return -1;
+}
+int main(int argc, char const *argv[])
+{
+	int n,key;
+	cout<<"Enter size of array: ";
+	cin>>n;
+	cout<<"Enter array elements: ";
+	int a[n];
+	for (int i = 0; i < n; ++i)
+	{
+		cin>>a[i];	
+	}
+	cout<<"Enter search key: ";
+	cin>>key;	
+	int res = binary_search(a,0,n-1,key);
+	if(res != -1)
+		cout<<key<<" found at index "<<res<<endl;
+	else
+		cout<<key<<" not found"<<endl;
+	return 0;
+}