RE: variable comparison

If all you are trying to do is determine the extension of a file, you can use the function
substr string, pos, [n, replacement]

which extracts and returns a substring n characters long, starting at position pos, from a given string. If pos is negative, the substring starts at the end of the string instead, so something like:

my $ext = ".htm";
my $filename = "filename.htm";

if ($ext eq substr ($filename, -4)) {
   #whatever
}
else {
   #whatever else
}
[download]

Also, substr can be put to more interesting uses. consider:

if n is omitted, everything to the end of the string is included.
if n is negative, that many chars are left off the end of the string.

For more information, consult Perl in a Nutshell,
ISBN 1-56592-286-7, published by O'Rielly.
Simplicus

Comment on RE: variable comparison Download Code

Replies are listed 'Best First'.
RE: RE: variable comparison by mdillon (Priest) on May 25, 2000 at 19:38 UTC
i like the substr approach myself, although i would make the small change of using the length function instead of hard coding the length of $ext. `if (substr($filename, -length($ext)) eq $ext) { # do stuff } else { # do other stuff }` [download]	[reply] [d/l]
RE: RE: RE: variable comparison by Simplicus (Monk) on May 25, 2000 at 20:19 UTC
Agreed. I've been brainwashed by Redmond to assume that an extension is three characters long. My early DOS training is to blame for that. (good ol' 8.3 notation, you know?) Using a regex to hunt for the dot is out of the question, because you might have a filename "foo.bar.htm" for example. Of course, you could always look for the last instance of the . in the filename, but . . . in the interst of having clearer code, I like the substr approach better than the regex (if only this once ;-) )	[reply]
RE: RE: RE: RE: variable comparison by mdillon (Priest) on May 25, 2000 at 20:28 UTC
for finding the last instance of a string in another string, you can use rindex.	[reply]


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