diff --git a/cpp/algorithm.h b/cpp/algorithm.h
new file mode 100644
index 0000000..4067138
--- /dev/null
+++ b/cpp/algorithm.h
@@ -0,0 +1,28 @@
+//
+//  algorithm_17.h
+//  2Term
+//
+//  Created by Kelvin Sherlock on 7/12/2016.
+//
+//
+
+#ifndef algorithm_17_h
+#define algorithm_17_h
+
+#include <algorithm>
+
+
+// c++17
+
+template<class T, class Compare>
+constexpr const T& clamp( const T& v, const T& lo, const T& hi, Compare comp ) {
+    return comp(v, hi) ? std::max(v, lo, comp) : std::min(v, hi, comp);
+}
+
+template<class T>
+constexpr const T& clamp( const T& v, const T& lo, const T& hi ) {
+    return clamp( v, lo, hi, std::less<T>() );
+}
+
+
+#endif /* algorithm_17_h */