Add exercice for module 14

exercises/14/README.md

@@ -1,3 +1,5 @@
 [< Back](../README.md)
 
+* [Exercise: Play with function parameters](parameters/README.md)
+
 * [Exercise: Create an isWall function](create_function/README.md)

exercises/14/parameters/README.md

@@ -0,0 +1,35 @@
+[< Back](../README.md)
+
+# Exercise: Pay with parameter passing
+
+In this exercise we will look together at what happens when we change a reference
+parameter to a value or a const reference.
+
+Let's look at this function
+
+```cpp
+void Game::processEvents(InputState & inputState) {
+
+
+ auto event = canvas.pollEvent();
+ if (event && event.value().type == sf::Event::Closed) {
+   inputState.close = true;
+   return;
+ }
+
+
+ inputState.down  = sf::Keyboard::isKeyPressed(sf::Keyboard::Key::Down);
+ inputState.up    = sf::Keyboard::isKeyPressed(sf::Keyboard::Key::Up);
+ inputState.left  = sf::Keyboard::isKeyPressed(sf::Keyboard::Key::Left);
+ inputState.right = sf::Keyboard::isKeyPressed(sf::Keyboard::Key::Right);
+}
+```
+
+
+## Exercise
+
+1. Make `inputState` a value. What happens when you compile the code? Can you explain why?
+
+2. Now make it a `const` reference. What happens? Can you explain why?
+
+3. Revert it back to a non-const reference an make sure the code compile.