Re^2: foreach type of deal?


#!/usr/bin/perl

use strict;
use warnings;


main(@ARGV);

sub main
{
    
    open(FH, "gtype.txt");
    foreach( my $line = <FH> ) {
        s/^g//; #toolic's idea.
}

}

    close FH;

#and kennethk's idea

#!/usr/bin/perl

use strict;
use warnings;

main(@ARGV);

sub main
{
    open(FH, "gtype.txt");
    while( my $line = <FH> ){
        substr($_,1); # Start with the second letter
}
}
[download]

So, using kennethk's input, I kind of hacked this up...? I can kind of see how it works...

I looked at the perldocs linked in the replies, and I'm still working through them trying to understand all the various differences.

the file I'm working with looks something like this:

gOrd_3342.png

gOrd_3343.png

500k of those going down a file. I need to leave all 500k of those with "Ord_xxxx.png. I have yet to try either of mentioned options, but my idea here is to figure this out and learn at the same time, and not simply get an answer I can plug in and call it quits. Thanks.

Comment on Re^2: foreach type of deal? Download Code

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Re^3: foreach type of deal? by huck (Prior) on Mar 15, 2017 at 20:41 UTC
Using `my $line = <FH>` means $_ never gets set so your next line needs to now be `$line=substr($line,1);`	[reply] [d/l] [select]
Re^4: foreach type of deal? by hoagies (Initiate) on Mar 15, 2017 at 20:56 UTC
Thanks! I just ran into that little bit :D. However, I read the perldoc about substr, and I get the idea. Now my question is, what modifies the string? substr just locates the particular part of the string I want to single out, then what? `#!/usr/bin/perl use strict; use warnings; main(@ARGV); sub main { open(FH, "gtype.txt"); while( my $line = <FH> ) { my $line = substr($line,1); printf $line; } } close FH;` [download] It works!! now what can I use to replace the printf, to use to delete?	[reply] [d/l]
Re^5: foreach type of deal? by huck (Prior) on Mar 15, 2017 at 21:19 UTC
now what can I use to replace the printf, to use to delete? You have now entered a situation i dont like. You seem to want to want to replace the original file. for the most part i dont like to do that (at first). I dont like to modify my only copy of the original data. What i do instead is write a new file, then use the new file in later processing. `use strict; use warnings; main(@ARGV); sub main { open(my $in ,'<', "gtype.txt"); open(my $out ,'>', "fixed-gtype.txt"); while( my $line = <$in> ) { my $line = substr($line,1); print $out $line; } } close $in; close $out;` [download] Note also the change from printf to print. You should read about what printf does in regards to the first argument being a format. What you wanted instead was print.	[reply] [d/l]
Re^6: foreach type of deal? by hoagies (Initiate) on Mar 15, 2017 at 21:47 UTC
Re^7: foreach type of deal? by huck (Prior) on Mar 15, 2017 at 21:50 UTC
Some notes below your chosen depth have not been shown here
Re^5: foreach type of deal? by kennethk (Abbot) on Mar 15, 2017 at 21:46 UTC
Subject to huck's well placed concerns about moving files on lists that haven't been manually inspected, look up rename or File::Copy. It's very easy to use these powerful tools to torpedo yourself. #11929 First ask yourself `How would I do this without a computer?' Then have the computer do it the same way.	[reply]