(bsearch)+algorithm implementation

Reads lines from "bsearch.txt", asks user for a number then binary
searches that number in the input data from "bsearch.txt".

bsearch.cpp

@@ -0,0 +1,57 @@
+/* bsearch.cpp
+ * Created: 2023-07-10
+ * Author: Aryadev Chavali
+ */
+
+#include <algorithm>
+#include <cstdlib>
+#include <fstream>
+#include <iostream>
+#include <string>
+#include <vector>
+
+using std::cin;
+using std::cout;
+using std::endl;
+using std::ostream;
+using std::string;
+using std::vector;
+
+vector<int> arr;
+
+ostream &print_arr(ostream &os)
+{
+  os << "[";
+  for (size_t i = 0; i < arr.size(); ++i)
+    os << arr[i] << (i == arr.size() - 1 ? "" : ",");
+  return os << "]";
+}
+
+int bsearch(int n, int l = 0, int u = arr.size() - 1)
+{
+  int midpoint = ((u + l) / 2);
+  if (l >= u || u <= 0)
+    return -1;
+  int val = arr[midpoint];
+  if (val == n)
+    return midpoint;
+  else if (val > n)
+    return bsearch(n, l, midpoint - 1);
+  else
+    return bsearch(n, midpoint + 1, u);
+}
+
+int main(void)
+{
+  std::ifstream input("bsearch.txt");
+  string line;
+  while (std::getline(input, line))
+    arr.push_back(std::stoi(line));
+  std::sort(std::begin(arr), std::end(arr));
+  string inp;
+  cout << "Enter number to search: ";
+  cin >> inp;
+  int to_search = std::stoi(inp);
+  cout << bsearch(to_search) << endl;
+  return 0;
+}