Solutions

Airspeed Velocity

Here is our version of the Airspeed velocity program code. When building your own version of this program, you can use this if you get stuck. Remember that your code may be a little different to this, and that is ok. The most important thing is that you create your own version, have a good understanding of how it works, and have developed the knowledge and skills necessary to create similar programs using variable and constant declarations, assignment statements, method calls, and an iterative process.

• Airspeed Velocity Code

  using static SplashKitSDK.SplashKit;
  using static System.Convert;
  
  const double STROUHAL_LOW_EFFICIENCY = 0.4;
  const double STROUHAL_HIGH_EFFICIENCY = 0.2;
  
  string birdName, line;
  double freq, amp;
  
  // Display program details
  WriteLine("Welcome to the Airspeed Calculator");
  WriteLine();
  
  // Read in the name, frequency and amplitude
  WriteLine("What is the name of the bird?");
  Write("Name: ");
  birdName = ReadLine();
  
  WriteLine("What is the frequency of its wing stroke? (beats per second)");
  Write("Frequency: ");
  
  // Read and convert frequency to double
  line = ReadLine();
  freq = ToDouble(line);
  
  WriteLine("What is the amplitude of its wings? (centi)");
  Write("Amplitude: :");
  line = ReadLine();
  amp = ToDouble(line);
  
  // calculate the airspeed, given a fixed Strouhal value
  double resultMax, resultMin;
  resultMax = freq * amp / STROUHAL_HIGH_EFFICIENCY;
  resultMin = freq * amp / STROUHAL_LOW_EFFICIENCY;
  
  // output the airspeed of the bird
  WriteLine($"Bird {birdName} ");
  WriteLine($" - f: {freq} A: {amp} Speed: {resultMax} m/s");
  WriteLine($" - f: {freq} A: {amp} Speed: {resultMin} m/s");

Water Bottle Visualiser

As with the Airspeed Velocity code, this is our version of the water bottle visualiser. Use it if you get stuck building your own version. As always, it is not important that your code matches this exactly. What is important is that you use this example to work through the thinking and coding skills needed to create programs using the concepts from this chapter.

• Watter Bottle Code

  using static System.Convert;
  using static SplashKitSDK.SplashKit;
  
  const int WINDOW_WIDTH = 600;
  const int WINDOW_HEIGHT = 600;
  
  /*-------------------------------------\
  | Water bottle shape...
  |
  | BOTTLE_LEFT_X     BOTTLE_RIGHT_X
  |        |             |
  |        v             v
  |          ___________
  |         /           \
  |   ^    |      x      | <-- x = BOTTLE_CENTER_X
  |   |    |\___________/|       + BOTTLE_TOP_Y
  |   |    |             |
  |   |    | ___________ |
  |   |    |/           \|
  |   |    |             | <-- waterY
  |   |    |\___________/| ^
  |   |    | ___________ | | waterHeight
  |   |    |/           \| v
  |   v    |             | <-- BOTTLE_BASE_Y
  |         \___________/
  | BOTTLE_HEIGHT
  |         <-----x-----> BOTTLE_RADIUS
  |        BOTTLE_DIAMETER
  \-------------------------------------*/
  
  const int BOTTLE_RADIUS = 80;
  const int BOTTLE_HEIGHT = 400;
  const int BOTTLE_DIAMETER = BOTTLE_RADIUS * 2;
  const int BOTTLE_CENTER_X = WINDOW_WIDTH / 2;
  const int BOTTLE_LEFT_X = BOTTLE_CENTER_X - BOTTLE_RADIUS;
  const int BOTTLE_RIGHT_X = BOTTLE_CENTER_X + BOTTLE_RADIUS;
  const int BOTTLE_BASE_Y = WINDOW_HEIGHT - BOTTLE_RADIUS - 5; // 5 pixel gap
  const int BOTTLE_TOP_Y = BOTTLE_BASE_Y - BOTTLE_HEIGHT;
  
  string line;
  int percentFull;
  
  WriteLine("Water Bottle Visualiser!");
  WriteLine();
  WriteLine("How full us your bottle? (0-100)");
  WriteLine();
  Write("Percent: ");
  line = ReadLine();
  
  // Convert the text entered to a double
  percentFull = ToInt32(line);
  
  double waterHeight = BOTTLE_HEIGHT * (percentFull / 100.0);
  double waterY = BOTTLE_BASE_Y - waterHeight;
  
  OpenWindow("Your Water Bottle", WINDOW_WIDTH, WINDOW_HEIGHT);
  ClearScreen(ColorWhite());
  
  // Draw the water
  // Circle at the top of the water
  FillCircle(ColorBlue(),  BOTTLE_CENTER_X, waterY, BOTTLE_RADIUS);
  
  // Circle at the bottom of the bottle
  FillCircle(ColorBlue(),  BOTTLE_CENTER_X, BOTTLE_BASE_Y, BOTTLE_RADIUS);
  DrawCircle(ColorBlack(), BOTTLE_CENTER_X, BOTTLE_BASE_Y, BOTTLE_RADIUS);
  
  // Draw the rest of the water
  FillRectangle(ColorBlue(), BOTTLE_LEFT_X, waterY, BOTTLE_DIAMETER, waterHeight);
  DrawCircle(ColorBlack(), BOTTLE_CENTER_X, waterY, BOTTLE_RADIUS);
  
  // Outline bottle
  // Draw the left wall of the bottle
  DrawLine(ColorBlack(), BOTTLE_LEFT_X, BOTTLE_BASE_Y, BOTTLE_LEFT_X, BOTTLE_TOP_Y);
  // Draw the right wall of the bottle
  DrawLine(ColorBlack(), BOTTLE_RIGHT_X, BOTTLE_BASE_Y, BOTTLE_RIGHT_X, BOTTLE_TOP_Y);
  DrawCircle(ColorBlack(), BOTTLE_CENTER_X, BOTTLE_TOP_Y, BOTTLE_RADIUS);
  
  RefreshScreen();
  Delay(5000);