- While Loops 3:55
- For Loops 3:15
- For Loops 1 objective
- Foreach Loops 4:04
- Foreach Loops 1 objective
- Magic Numbers and Constants 3:13
- Constants 1 objective
- Putting It All Together 5:13
- Commenting 1:50
- Commenting Code 3 questions
- Playing the Game 4:59
- Static Members 4:39
- Static Members 1 objective
- Using Static Fields 3:40
- Wrap Up 2:30
- Wrap-up 2 questions
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Using Static Fields
3:40Static fields, like static methods, are called directly on the class name - unless you're already in the class.
Now that we have a random
number generator.
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Let's use it to make it possible for the
towers to occasionally miss their targets.
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Let's start by deciding how accurate
we want our towers to be and
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then make that a constant.
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We'll set the accuracy to .75.
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Meaning on average 75% of the time
the tower will hit its target.
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No let's create a method
that when called returns
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true when the tower
successfully hits the target.
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We'll call it IsSuccessfulShot.
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Now here's where we can use
our random number generator.
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We can ask for a number between zero and
one by calling NextDouble, and
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return true if the number generated
is less than the accuracy.
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The .NET random number
generator is uniformly random,
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meaning every value between zero and one
has an equal chance of being generated.
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So 75% of the time it will generate
a number between zero and 0.75.
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So if the number it
generates is less than 0.75,
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we'll count that as hitting
the target otherwise it's a miss.
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Notice that here,
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when using the random field,
we're referencing the Tower class name.
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This is how we use static
members of a class.
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Actually, this is only necessary
when accessing the number from
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outside the class in order to
state which class is being used.
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However, since we're already in
the Tower class, we don't need this.
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We could type it here but
we don't need to.
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We can just use it like any
other field in the class.
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What we can't do is type this,
because this
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refers to the current object and the
object doesn't have the random variable.
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Only the Tower class itself has one.
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Now we can check for successful shots
in the fire on invaders method.
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We only want to decrease the health of the
invader the tower attempts to shoot at,
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if it's a successful shot.
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So I'll wrap this call to decrease
health by this if statement like so.
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To see what's happening
while the game runs,
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let's print the results
to the console here.
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Let's add the system namespace
to the top of the file.
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And we can remove references to it here.
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Now, let's print something
if it's a successful shot.
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So I'll say, shot at and hit an invader.
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Let's print something else if they miss.
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We'll say, shot at and missed an invader.
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Don't forget to type else here.
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Let's also print something if
the invader has been neutralized.
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So I’ll say if invader.IsNeutralized.
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Then we'll print Neutralized an invader.
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Now let's compile and run the game
to see how this changes things.
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As you can see, the player wins
sometimes and loses sometimes.
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Adding a little randomness increases
the challenge of playing the game.
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