Updating file name

F/lix has asked for the wisdom of the Perl Monks concerning the following question:

Hello all, I have to repeat 15 times the same operation writing (different) data into .dat files. The basic name of the file is user-defined and stored in a variable, say $File. What I'd like to do is to add an extension to that file name to have something like : File1.dat, File2.dat and so on. I've tried to put all this in a FOR loop but it obviously doesn't work. Here's part of what I've done:

! for ($j=1;$j<=2;$j++) {
!  $FileName= $File$j.dat;
! }
[download]

The problem seems to be in the two $ that appear there. How do you solve the problem? Many thanks, Felix

Comment on Updating file name Download Code

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Re: Updating file name by ikegami (Patriarch) on Aug 04, 2006 at 19:05 UTC
Use the string concatenation operator `$FileName= $File . $j . ".dat";` or use interpolation `$FileName= "$File$j.dat";` By the way, `for (my $j=1;$j<=2;$j++)` is not nearly as readable as `for my $j (1..2)`	[reply] [d/l] [select]
Re: Updating file name by imp (Priest) on Aug 04, 2006 at 19:08 UTC
You either need to concatenate the values using '.': `$FileName= $File . $j . '.dat';` [download] Or interpolate them inside double quotes: `$FileName= "$File$j.dat";` [download] Or you can always use sprintf: `$FileName= sprintf '%s%d.dat', $File, $j;` [download]	[reply] [d/l] [select]
Re: Updating file name by friedo (Prior) on Aug 04, 2006 at 19:05 UTC
You can use Perl's concatenation (dot) operator to combine strings: `for(1..2) { my $filename = $file . "$_.dat"; }` [download] Update: s/j/_/;	[reply] [d/l]
Re: Updating file name by F/lix (Initiate) on Aug 04, 2006 at 19:18 UTC
Many thanks. Sometimes it's just too simple!	[reply]
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