problem in substitution

azaria has asked for the wisdom of the Perl Monks concerning the following question:

Hello,
I have a problem in substitute 2 directory names, for e.g:

$dir1="D:\\Windows\\programs1";
$dir2="D:\\Windows\\programs2";

$file1 = ="D:\\Windows\\programs1\\a.txt";

($file2 = $file1) =~ s/$dir1/$dir2/esg;

print "file1 -> $file1\n";
print "file2 -> $file2\n";
[download]

I expect to get -

file1 -> D:\Windows\programs1\a.txt
file2 -> D:\Windows\programs2\a.txt
[download]

but i got -

file1 -> D:\Windows\programs1\a.txt
file2 -> D:\Windows\programs1\a.txt
[download]

Any idea ?

Thanks in advance

azaria

Comment on problem in substitution Select or Download Code

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Re: problem in substitution by ccn (Vicar) on Dec 08, 2008 at 07:31 UTC
`($file2 = $file1) =~ s/\Q$dir1/$dir2/;` [download] Since you have backslahes inside of the pattern you need use \Q to disable pattern metacharacters. Also you don't need any modifiers (esg) for the regexp, excepting i probably. see perldoc perlre	[reply] [d/l]
Re: problem in substitution by poolpi (Hermit) on Dec 08, 2008 at 09:00 UTC
Portably perform operations on file names This core module may help you : File::Spec `#for example my ($volume,$directories,$file) = File::Spec->splitpath( $path, $no_file );` [download] hth, PooLpi 'Ebry haffa hoe hab im tik a bush'. Jamaican proverb	[reply] [d/l]
Re: problem in substitution by rminner (Chaplain) on Dec 08, 2008 at 13:16 UTC
Just like poolpi said, File::Spec is the way to go. Substituting a directory segment of a path can be annoying, because paths tend to be specified in different formats. For example: File::Find under windows returns the results with a slash appended, even though the path was specified using backslashes. In such cases you have a mixed syntax of slashes and backslashes. If you use File::Spec, you won't have to worry about the specific syntax of a path. Example: `use File::Spec; # Example with mixed syntax my $old_dir = "D:\\Windows\\programs1"; my $new_dir = "D:\\Windows/programs2"; my $old_fn = "D:/Windows/programs1/a.txt"; my $rel_path = File::Spec->abs2rel($old_fn, $old_dir); my $new_fn = File::Spec->catfile($new_dir , $rel_path); print "New Filename: $new_fn\n"; # or combine both: my $new_fn2 = File::Spec->catfile($new_dir , File::Spec->abs2rel($old_ +fn, $old_dir)); print "New Filename2: $new_fn2\n";` [download]	[reply] [d/l]
Re: problem in substitution by spmlingam (Scribe) on Dec 08, 2008 at 10:56 UTC
If you want to enable the pattern meta characters in the regular expression again, you can use \E (\Q will disable pattern metacharacters till \E.)	[reply]