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9.1 Standard Output and the print Operator

By default output from a Perl program goes to the standard output stream. The basic operator for this output is the print operator. Essentially the print operator is passed a list of items and outputs them to the standard output stream.

Values passed to print can be in a number of forms. For example:

A string value:

 print "Hello my name is Fred\n";

A string variable:

$name="fred";
print $name;

A mathematical calculation:

 print 2+4;

Or even a mixture of the three:

 print "I asked $name and he told me 2+4 equals ", 2+4, ".\n";

which will display:

 I asked fred and he told me 2+4 equals 6.

The print operator can also be used to print an array:

 print @array;

The above command will print all the items contained in an array. For example:

#!/usr/bin/perl
@colorarray = qw { white red green blue yellow black };
print @colorarray;

will output each element of the array. Note that none of the elements in the array have newline characters so they are all displayed on the same line:

 whiteredgreenblueyellowblack

To display the array as an interpolated array put the array in double quotes:

#!/usr/bin/perl
@colorarray = qw { white red green blue yellow black };
print "@colorarray";

The print command treats the array as though it had been interpolated into a string variable and will output the values as a single string separated by spaces:

 white red green blue yellow black 

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