46 lines
1.8 KiB
Markdown
46 lines
1.8 KiB
Markdown
[< Back](../README.md)
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# Exercise: Create an isWall function
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In this exercise we will write some helper functions for the game board.
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The file [`Board.cpp`](../../../lib/Board.cpp) defines functions to manipulate the game Board, for example finding where
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the walls and the portals are.
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## Background: Board.cpp
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The Board itself is represented in memory as a 2 dimensional array. A cell in this grid can be for example walkable, a
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wall, a pellet, a super pellet or a portal.
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`Cell` is an enum representing the different types of cells.
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`isWalkableForGhost` and `isWalkableForPacMan` are two functions which need to check whether a cell is a wall.
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```cpp
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bool isWalkableForPacMan(GridPosition point) {
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return cellAtPosition(point) != Cell::wall && cellAtPosition(point) != Cell::pen;
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}
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bool isWalkableForGhost(GridPosition point, GridPosition origin, bool isEyes) {
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const Cell cell = cellAtPosition(point);
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if (cell == Cell::wall)
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return false;
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return isEyes || isInPen(origin) || !isInPen(point);
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}
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```
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## Exercise
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Let's add a simple helper function.
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You might notice that `isWalkableForPacMan` and `isWalkableForGhost` both call `cellAtPosition` with a `GridPosition`
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variable and check if it is a wall. Maybe we can lift that check into a separate function (call it `isWall`) to avoid
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repeating ourselves?
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1. Create a function called `isWall` between `cellAtPosition` and `isWalkableForPacMan` that returns true if
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the `GridPosition` parameter is a wall. A function needs to be defined before it is called, so the order of functions
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is important. Try to define `isWall` after ``isWalkableForPacMan` or before `cellAtPosition`. It does not compile
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2. Replace the checks within `isWalkableForPacMan` and `isWalkableForGhost` with your new function.
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3. Check to see that the game still works as expected.
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