Added binary search algorithm in C#

code/binary_search-anksos.cs

@@ -0,0 +1,37 @@
+// LANGUAGE: C#
+// TOPIC: Iterative Implementation of binary search algorithm
+using System;  
+class GFG { 
+	// Returns index of x if it is present in arr[],  
+    // else return -1 
+    static int binarySearch(int []arr, int x) { 
+        int l = 0, r = arr.Length - 1; 
+        while (l <= r) { 
+            int m = l + (r-l)/2; 
+            // Check if x is present at mid 
+            if (arr[m] == x) 
+                return m; 
+            // If x greater, ignore left half 
+            if (arr[m] < x) 
+                l = m + 1; 
+            // If x is smaller, ignore right half 
+            else
+                r = m - 1; 
+        } 
+        // if we reach here, then element was  
+        // not present 
+        return -1; 
+    } 
+    // Driver method to test above 
+    public static void Main() { 
+        int []arr = {2, 3, 4, 10, 40}; 
+        int n = arr.Length; 
+        int x = 10; 
+        int result = binarySearch(arr, x); 
+        if (result == -1) 
+            Console.WriteLine("Element not present"); 
+        else
+            Console.WriteLine("Element found at " +  
+                                "index " + result); 
+    } 
+}