SAMS Teach Yourself Perl in 24 Hours THIRD EDITION

Scoping Revisited

In Hour 5, “Working with Files,” you learned about variables and variable scope. Specifically you learned that the my keyword declares that a variable is local only to the program, or to any curly braces that might be around it. Look at the example in Listing 17.3.

Listing 17.3. Small Scoping Example

1: #!/usr/bin/perl –w 2: 3: use strict; 4: my $max = 15; 5: 6: sub read_max { 7: my $counter = 0; 8: 9: while(<DATA>) { 10: my $line = $_; 11: if ($counter++ < $max) { 12: print $line 13: } 14: } 15: } 16: read_max();

The variable $max is visible anywhere within the program, $counter is visible only within the subroutine, and $line is visible only within the while loop.

In Hour 5, I said that with strict in place you had to declare ...