Tinkering with Perl

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Assignment of scalars

There are a few ways to assign a scalar. You can assign a scalar to a given value:

$NumberOfCats = 5;
$MyCatsName = "Zappy";

Or you can assign one variable using another:

$NumberOfNoses = $NumberOfPeople;

This tells the computer that the number of noses is the same as the number of people. Or, to put it another way, it takes the value stored in the variable NumberOfPeople, and stores a copy of it in $NumberOfNoses.

There are several things that you can do with a string. One useful thing you can do is concatenate two strings. For example, if you concatenate the strings "My cat's name" and " is Zappy.", you get, "My cat's name is Zappy."

Did you notice the space between the quotation mark and the "is"? That space is important. Computers don't know when you should add a space to separate words. If you concatenate "My cat's name" and "is Zappy." without the extra space, it would come out, "My cat's nameis Zappy."

In Perl, you can concatenate two strings by putting a period between them. For example, you could get the whole sentence like so:

$WholeSentence = "My cat's name" . " is Zappy.";

Or, to do it differently,

$FirstPartOfSentence = "My cat's name";
$SecondPartOfSentence = "is Zappy.";
$WholeSentence = $FirstPartOfSentence . " " . $SecondPartOfSentence;

Do you see what I did here? I didn't have a space before "is" in SecondPartOfSentence, but I put another space in between the two parts. There were three strings here: $FirstPartOfSentence, " " (a string consisting of only a space), and $SecondPartOfSentence. I concatenated all of them together, just as you add 3 + 1 + 2 to get 6. Putting in an extra space can come in handy, when you want to make text look good.

There are other ways to assign scalars, and they will be covered when we discuss arithmetic and functions.

Tinkering with Perl

Assignment of scalars

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