Perl String Substring

Question

I want to replace something in a way like C:\foo , so I:

 s/hello/c:\foo 

But this is not true. Do I need to avoid some characters?

Answer 1

Two problems that I see.

Your first problem is that your s/// replacement is not complete:

 s/hello/c:\foo # fatal syntax error: "Substitution replacement not terminated" s/hello/c:\foo/ # syntactically okay s!hello!c:\foo! # also okay, and more readable with backslashes (IMHO) 

The second problem you asked for is that \f is taken as a feed escape sequence (ASCII 0x0C), just like it would be in double quotes, which you don't want.

You can either avoid the backslash, or let the interpolation of variables “hide” the problem:

 s!hello!c:\\foo! # This will do what you want. Note double backslash. my $replacement = 'c:\foo' # NB: Using single quotes here, not double quotes s!hello!$replacement!; # This also works 

Take a look at the treatment of Quote and Quote perlop in perlop for more information.

Answer 2

If I understand what you are asking, it could be something like what you need:

 $path = "hello/there"; $path =~ s/hello/c:\\foo/; print "$path\n"; 

To answer your question, yes, you need to double the backslash because \f is the escape sequence for "form feed" in the Perl line.

Answer 3

The problem is that you are not avoiding special characters:

 s/hello/c:\\foo/; 

will solve your problem. \ is a special character, so you need to avoid it. {}[]()^$.|*+?\ are meta (special) characters that you need to avoid.

Additional link: http://perldoc.perl.org/perlretut.html