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Ping Pong
7:32In this video, we'll create a simple ping pong game to demonstrate another use case for while loops.
I'm going to show you some
other loops that I prefer
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when it comes to looping through arrays.
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But I don't want you to think
that while loops are unimportant.
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Let's create a simple ping pong game
to demonstrate another use case for
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while loops.
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Let's create a new file named
pingpong.php We add our PHP tags.
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And then we're ready to
start programming the game.
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We'll start with two players,
each with an initial score of 0.
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$player1 = 0.
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And $player2 = 0.
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I also want to track how
many rounds each game takes.
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So I'm going to add another variable.
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$round = 0.
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Now let's add some comments.
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To win,
a player must reach the score of 11.
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While also being a minimum of 2
points higher than their opponent.
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So while those conditions are not met.
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I'm going to randomly increment one
of the player's scores each round.
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To check for
the difference between the player scores,
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I can subtract one score from the other.
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This will give me a number
that can be positive or
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negative depending on
which score is higher.
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We can then find the absolute
value of that number.
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Let me demonstrate.
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Let's change $player2 = 5.
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Then we'll do a var_dump.
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$player1- $player2.
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Then we'll also var dump
$player2- $player1.
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Let's run the script.
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I see that the first var dump shows -5 and
this the second var dump shows 5.
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The difference between these numbers is 5.
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All I care about is that the difference
between these numbers is greater than 2.
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I don't care which is the higher number.
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So, I can use a function to
determine the absolute value, abs.
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I'll add this to the first var_dump.
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Now, when I run my script.
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You can see that the absolute
value gives me the number itself,
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without the negation before it.
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I can use this absolute
value in my while loop.
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Let’s comment out these var dumps.
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So I want to continue to loop while
the absolute value is less than 2.
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I also want to continue to loop
while both scores are less than 11.
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So I'm going to add a second expression.
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I’ll combine these with the double pipe
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operator because I want either or
to be true.
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$player1 is less than 11 and
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$player2 is less than 11.
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I need to put parenthesis
around these two expressions so
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that they evaluate as
a single conditional.
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$player1 must be less than 11 and
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$player2 must be less than
11 to continue my loop.
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So if the difference between the players
is less than 2, we'll continue to loop.
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Or if $player1 and $player2 are both
less than 11 we will continue to loop.
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The first thing I want to do is
to start incrementing the round.
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This would be round 1.
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So adding 1 to 0 = 1.
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Let's also let the user know
what's going on with each loop.
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So let's start with the heading for
the round.
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I want to view this in the browser,
so let's add the HTML tags.
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Round $round, And close my tags.
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Notice that I used the double quote,
so that my variable is expanded.
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Now we want to randomly add a point
to either $player1 or $player2.
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PHP has a function named RAND that
will generate a random integer.
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We can specify a minimum and
a maximum for this random integer.
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So we can say if {rand(0,1)
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then we're going to do something.
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The min and max are inclusive,
meaning it will include the minimum and
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the maximum in its random
number generation.
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With a minimum of 0 and a maximum of 1,
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we will randomly receive either 0 or 1.
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Since 0 evaluates to false and
1 evaluates to true,
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we can use this in our conditional.
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If 1 is returned and our expression
is true, we can add 1 to $player1.
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Else we can add 1 to $player2.
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Now, let's display the current score for
this round.
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Player1 = $player1 score and a line break
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Player2 = $player2 score and a line break.
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And that's all we need for a while loop.
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So let's preview this script in a browser.
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We can see each round with a point
being awarded to a random player.
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And the final score ending with
Player1 = 2 and Player2 having 11.
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This is okay, but
let's add a final summary.
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After our while loop, we should add
our comment back up in the while loop.
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And after our comment we can add echo header 1.
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If $player1 > $player2,
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we'll echo Player1.
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Else we'll echo Player2.
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And finally we'll echo,
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is the winner after $round rounds.
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And close our header.
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Let's preview our script again
to see the final result.
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Player 2 is the winner after 9 rounds.
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