Hi Monks
I'm struggling a little with typeglobbing and filehandles. I've read this excellent node and more besides
What I can't figure out is why does this NOT work:
#assume files a.txt and b.txt exist and are normal, readable files.
use strict;
use warnings;
open(FILE_A,"<","a.txt") || die "Could not open file 'a.txt': $!\n";
open(FILE_B,"<","b.txt") || die "Could not open file 'b.txt': $!\n";
my @FH=(*FILE_A,*FILE_B);
for(my $i=0;$i<2;$i++){
while(my $line=<$FH[$i]>){
print "line: $line\n";
}
}
exit(0);
(And it also doesn't work if you try any of the following:
- *FILE_A -> \*FILE_A
- $FH[$i] -> *$FH[$i]
- $FH[$i] -> ${FH[$i]}
- *FILE_A -> \*FILE_A && $FH[$i] -> *$FH[$i]
etc.. the point being I've tried quite a few things.
Specifically the problem is that
File::glob::csh_glob returns
undef,
except when you do
when it returns "GLOB(0x52f9f0)" (obv memory address changes..), but then the output is
line: GLOB(0x52f9f0)
However, this works!!
#...as before...
for(my $i=0;$i<2;$i++){
my $fh=$FH[$i]; # <----**
while(my $line=<$fh>){
#...as before...
And it still works whether
or not...
Why? What's the difference? Am I missing something fundamental here? Or is this some kind of 'feature'? Or is the first syntax ambiguous, or.. what??
Cheers
why_bird
edit: Formatting issues!
edit: ">" to "<", thanks Fletch
........
Those are my principles. If you don't like them I have others.
-- Groucho Marx
.......
-
Are you posting in the right place? Check out Where do I post X? to know for sure.
-
Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
<code> <a> <b> <big>
<blockquote> <br /> <dd>
<dl> <dt> <em> <font>
<h1> <h2> <h3> <h4>
<h5> <h6> <hr /> <i>
<li> <nbsp> <ol> <p>
<small> <strike> <strong>
<sub> <sup> <table>
<td> <th> <tr> <tt>
<u> <ul>
-
Snippets of code should be wrapped in
<code> tags not
<pre> tags. In fact, <pre>
tags should generally be avoided. If they must
be used, extreme care should be
taken to ensure that their contents do not
have long lines (<70 chars), in order to prevent
horizontal scrolling (and possible janitor
intervention).
-
Want more info? How to link
or How to display code and escape characters
are good places to start.