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The for loop enables us to iterate over a sequence of numbers and repeat the same set of operations for each number.

For example, the following program prints all the numbers from 1 to 100:

for $i (1..100) { print $i, "\n"; }

Some explanations about the syntax:

`$i`

is the iteration variable. It receives the value 1, then the value 2, then 3 and so forth until it is equal to 100, afterwards the loop terminates.- The curly brackets (
`{ ... }`

) encapsulate the loop block. The loop block is executed once for each value`$i`

accepts. Within that block, called the loop body, you can use`$i`

and you'll get its current value.

We can nest loops, so for example the following program prints the multiplication board:

for $y (1 .. 10) { for $x (1 .. 10) { $product = $y*$x; # Add as much whitespace as needed so the number will occupy # exactly 4 characters. for $whitespace (1 .. (4-length($product))) { print " "; } print $product; } # Move to the next line print "\n"; }

You may have noticed the program's comments. In perl comments start with the sharp sign (`#`

) and extend to the end of the line. Writing the multiplication boards with the labels that indicate which numbers are being multiplied is left as an exercise to the reader.

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Written by Shlomi Fish