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This pattern of using an integer that
increases each time the loop runs, is so

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common that there's a special
kind of loop just for that.

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It's called a for loop.

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I'll write what that looks like lower
existing loops so we can compare the two.

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This is doing

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exactly the same

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thing the while loop, up here does.

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We can break our while loop
up here into for parts.

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First, we declare index as an integer and
initialize it to 0.

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Second, we check to see if we’ve looped
through all the indexes of the array.

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Third, we do something with each of the
array items Fourth, we increment index so

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that the next time through the loop we're
getting the next item in the array.

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For loops also have the same for
parts only there written more concisely.

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Here's where we declare index as
an integer and initialize it to zero.

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Here's where we check to see if we've loop
through all the indexes of the array.

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The body of the loop is used for
doing something with the array item.

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And here's where we increment index so

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that the next time through the loop we're
getting the next item in the array.

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Just think of for loops
as condensed while loops.

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Now that we have this for loop we
don't need this while loop anymore.

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For loops aren't only used for
looping through a race.

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They're also really handy when we want
to count from one number to another.

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We can set the starting number here and
it can be any number we want.

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We decide where to stop counting here.

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This can be any condition that eventually
stops the loop by evaluating to false.

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Each time the loop runs,
index will count up by one.

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In fact, this variable is
often called a loop counter.

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We could also count by more than
one by using plus equals like this.

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This will count up by two.

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We want to count by one so
I'll change this back to index plus plus.

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Because this variable index
is being declared right here,

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its scope is limited
to inside of the loop.

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That means that it can only
be used inside the 4 loop.

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If we want to access the loop counter
variable after the 4 loop has ended,

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we'd have to move the declaration
up here above the 4 loop somewhere.

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[PAUSE] It may look strange, but
this is perfectly valid code.

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When reading code, you'll notice that
most for loops use the single letter I

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as the name of the loop counter variable.

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This tradition goes all the way back to
the first programming languages created.

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You can name it whatever makes sense for
your code though.

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Just to maintain tradition I'll
shorten index to I for us.