variable value substitution

wtolentino has asked for the wisdom of the Perl Monks concerning the following question:

i have simple code that will check for a matching string. if the string is found i need to substitute it with a new string. how do i accomplish it? i am a begginer. thank you.

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$nDateStamp = $month . $day . $year;

$filename = '17000_DM161_082511.dat';

if (index($filename,$tDateStamp) != -1) {
  print "found\n";
  # substitute the 082511 with the $nDateStamp
  # results in '17000_DM161_082411.dat
}
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Re: variable value substitution by toolic (Bishop) on Aug 25, 2011 at 16:27 UTC
Use the substitution operator: `use warnings; use strict; my $nDateStamp = '082411'; my $filename = '17000_DM161_082511.dat'; print "$filename\n"; $filename =~ s/082511/$nDateStamp/; print "$filename\n"; __END__ 17000_DM161_082511.dat 17000_DM161_082411.dat` [download]	[reply] [d/l]
Re^2: variable value substitution by wtolentino (Initiate) on Aug 25, 2011 at 17:34 UTC
thanks so much that works.	[reply]
Re: variable value substitution by zentara (Cardinal) on Aug 25, 2011 at 16:33 UTC
Do you need to rename the file too? If so, in addition to what toolic showed `rename($filename, $new_filename)` [download] Just changing the string, won't actually change the name of the .dat file on the disk. I'm not really a human, but I play one on earth. Old Perl Programmer Haiku ................... flash japh	[reply] [d/l]
Re: variable value substitution by ww (Archbishop) on Aug 25, 2011 at 19:43 UTC
This is the kind of question which could be answered with a minimal expenditure of effort on Google or with Super Search. The following will explain why failing to try self-help first is a mistake and may help you avoid a repeat: On asking for help How do I post a question effectively? I know what I mean. Why don't you?	[reply]
Re: variable value substitution by ajose (Acolyte) on Aug 25, 2011 at 17:58 UTC
For substitution, you can use ~s///. This will just substitute the file date with your date. Also the result has a date 082411. I assume that $nDateStamp holds this value. And $tDateStamp holds 082511. `$nDateStamp = '082411'; $tDateStamp = '082511'; $filename = '17000_DM161_082511.dat'; if (index($filename,$tDateStamp) != -1) { $filename =~ s/$tDateStamp/$nDateStamp/; print "found\n$filename\n"; }` [download] Or in a better way: `$nDateStamp = '082411'; $tDateStamp = '082511'; $filename = '17000_DM161_082511.dat'; if ( $filename =~ s/$tDateStamp/$nDateStamp/) { print "found\n$filename\n"; }` [download]	[reply] [d/l] [select]