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I have this perl code:

my($line) = $_;
chomp($line);
$line =~ tr/[a-z]/[A-Z]/;

I need to test if the first two character of a line in a text file "2:"

What would I use to test such a condition?

The following just loops through a file and checks whether each line starts with 2: - is that all you wanted it to do?

Code:

open( REPORT, "afile.txt" ) || die "Can't open afile.txt: $!\n";

while ( $line = <REPORT> ) {

  if ( $line =~ m/^2:/ ) {

    print "It matches!\n";

  }

}

close( REPORT ) || die "Can't close afile.txt: $!\n";

What I need to get is

2:06/06/07 15:49 is my $line

is the complete string... I want to test for just the first 2:

if ( $line =~ m/^2:/ )

Will this do that? or do I need to break it down to the first two characters?

I might not be understanding you properly, but...

$line =~ m/^2:/ will test the first 2 characters of $line and does not change $line. If you use $line after matching, it will have the same value as it had before matching. So if $line was 2:06/06/07 15:49 before the match, it is still 2:06/06/07 15:49 after the match.

If you want to know what happens during a match, perl sets several variables you can use after the match statement. Perl sets $` to the string preceding the match, it sets $& to the string that was matched and it sets $' to the string following what was matched. For the example of 2:06/06/07 15:49 this is what they would be:

Code:

$` would be the empty string at the start of the line

$& would be 2:

$' would be 06/06/07 15:49

$line would be 2:06/06/07 15:49

Using these variables can cause a performance hit, so test them if you want to use them with large files.

Hope that helps...