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Lesson 11
Objective
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The Join Function in Perl Perl Join Function to format arrays |
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The
join and split functions are tremendously useful for working with arrays.
You will find that you use these two functions quite often as a convenient method of formatting arrays for both display and storage. In this lesson, we'll examine the use of join, and in the next we'll look at the use of
split.We have already used the join function in the array examples in the previous lessons, but here I'll give you a more formal
definition of the syntactical structure:join separator, LIST The separator is any scalar, and the LIST is any list of scalars (including an array). A common use of this function is to print a comma-separated list of an array: @array = ("Black", "Brown", "Polar", "Grizzly"); print join(', ', @array), "\n"; Black, Brown, Polar, Grizzly
Function Calls in Perl
Even though the parenthesis are not required for built-in functions in Perl,
it's a good idea to use them when the function call is not the only element in the
statement.
Otherwise (due to the different leftward and rightward precedence) you may not always get the result you want. For example, if you remove the parenthesis from the join in the above code, the "\n" becomes part of the list being passed to join, so you will get this output instead:Black, Brown, Polar, Grizzly Another common usage for join is to delimit an array for storage in a flat file. Later the delimited data can be read back
into an array with split. Here's an example:
@array = ("Black", "Brown", "Polar", "Grizzly");
bgcolor="#EAEAEA"print join(':', @array), "\n";
That prints the array with colons separating the elements like this:
Black: Brown: Polar: Grizzly
To put them back into an array, you can use the split function.
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