字符串替换

Question

I have the following string ./test and I want to replace it with test so, I wrote the following in perl: my $t =~ s/^.//; however, that replaces ./test with /test can anyone please suggest how I fix it so I get rid of the / too. thanks!

Answer 1

my $t =~ s/^\.\///;

You need to escape the dot and the slash.

The substitution is s/match/replace/ . If you erase, it's s/match// . You want to match "starts with a dot and a slash", and that's ^\\.\\/ .

Answer 2

The dot doesn't do what you expect - rather than matching a dot character, it matches any character because of its special treatment. To match a dot and a forward slash, you can rewrite your expression as follows:

my $t =~ s|^\./||;

Note that you are free to use a different character as a delimiter, in order not to confuse it with any such characters inside the regular expression.

Answer 3

If you want to get rid of ./ then you need to include both of those characters in the regex.

s/^\.\///;

Both . and / have special meanings in this expression ( . is a regex metacharacter meaning "any character" and / is the delimiter for the s/// operator) so we need to escape them both by putting a \\ in front of them.

An alternative (and, in my opinion, better) approach to the / issue is to change the character that you are using as the s/// delimiter.

s|^\./||;

This is all documented in perldoc perlop .

Answer 4

You have to use a backward slash before the dot and the forward slash: s/\\.\\//; The backslash is used to write symbols that otherwise would have a different meaning in the regular expression.

Answer 5

You need to write my $t =~ s/^\\.\\///; (Note that the period needs to be escaped in order to match a literal period rather than any character). If that's too many slashes, you can also change the delimiter, writing instead, eg, my $t =~ s:^\\./::; .

Answer 6

$t=q(./test);$t=~s{^\./}{};print $t;

You need to escape the dot if you want it to match a dot. Otherwise it matches any character. You can choose alternate delimiters --- best when dealing with forward slashes lest you get the leaning-toothpick look when you otherwise need to escape those too.

Answer 7

Note that the dot in your question is matching any character, not a literal '.'.

my $t = './test';
$t =~ s{\./}{};

Answer 8

use Path::Class qw( file );
say file("./test")->cleanup();

Path::Class