What is perl symbol =~

Question

I am using someone else's text parsing perl code and I'd like to make some modifications. Could someone explain what =~ symbol is doing?

$xmlfile =~ s/value="{(.*?)}"/'value="'.&subst($1).'"'/ge;

EDIT:

So I found this thread that explains part of the regex string.

http://www.perlmonks.org/?node_id=24640

Tip: you can search for funky syntax on this site. Use the search string `[perl] "=~"` and you'd have had your answer. — Mat, May 05 '14 at 05:35
@Thilo Not really. I understand that it is doing some kind of string matching and runs subst() function on the matched string, but I don't really understand the details. Explanation would be appreciated. Thanks! — Tayyar R, May 05 '14 at 19:54

score 1 · Accepted Answer · answered May 05 '14 at 05:35

1

By default, matching, substitution, or transliteration act on $_; to use them on another variable, the binding operator =~ is used. In your case, the variable the substitution will be performed on is $xmlfile.

answered May 05 '14 at 05:35

ysth

96,171
6
121
214

So is $xmlfile passed into $1? Or whatever is matched by s/value="{(.*?)}" is passed into $1? – Tayyar R May 05 '14 at 19:55
`$1` is what is captured by the `(.*?)` so is what is found inside the curly braces. $xmlfile is the string it will be looking through and substituting in. – ysth May 05 '14 at 20:33

score 0 · Answer 2 · answered May 05 '14 at 05:34

According to perlop:

Binary "=~" binds a scalar expression to a pattern match. Certain operations search or modify the string $_ by default. This operator makes that kind of operation work on some other string. The right argument is a search pattern, substitution, or transliteration. The left argument is what is supposed to be searched, substituted, or transliterated instead of the default $_.

What is perl symbol =~

2 Answers2