string concatenation, which way is better?

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

HI
I am new to Perl and want to know if there is difference in below declaration
Type 1:

my $filename=sprintf("%s/filename1.log.%s",$file_dir,$todayDate);
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Type 2:

my $filename="${file_dir}/filename1.log.${today_date}";
[download]

I know both declarations will work, but want to know which is good practice and if there is any reason for the same.
Thanks in advance.

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Re: string concatenation, which way is better? by trizen (Hermit) on Aug 08, 2012 at 21:27 UTC
Both are good, but if you concatenate files and want to make your code portable, I recommend the File::Spec::Functions module. Something like this: `use File::Spec::Functions qw(catfile); my $filename = catfile($file_dir, q{filename1.log.} . $today_date);` [download] Back on the topic. The following codes are equivalent: `1. $this . q{/} . $that` `2. join(q{/}, $this, $that)` `3. "$this/$hat"` `4. do{local $"=q{/}; "@{[$this, $that]}"}` `5. sprintf('%s/%s', $this, $that)` Most used are: 1, 2, 3.	[reply] [d/l] [select]
Re: string concatenation, which way is better? by frozenwithjoy (Priest) on Aug 08, 2012 at 21:39 UTC
Personally, I've found the following approach to be more readable and easier to maintain: `my $filename = $file_dir . "/filename1.log." . $today_date;` [download] However, if you don't like the concatenation operator for some reason, you can just go with: `my $filename = "$file_dir/filename1.log.$today_date";` [download]	[reply] [d/l] [select]
Re: string concatenation, which way is better? by johngg (Canon) on Aug 08, 2012 at 22:09 UTC
You seem to be a little inconsistent with your variable names between the two code examples, `$todayDate` in one and `$today_date` in the other, so you may have a typo in your script. I don't know how you initialise your `$todayDate` variable. If you generate it programmatically in your code rather than reading it from a file you may find the `strftime()` function of the POSIX module along with localtime and time useful. `$ perl -MPOSIX=strftime -E ' > $file_dir = q{/var/log}; > say strftime qq{$file_dir/filename1.log.%F}, localtime( time() );' /var/log/filename1.log.2012-08-08 $` [download] I hope this is helpful. Cheers, JohnGG	[reply] [d/l] [select]
Re: string concatenation, which way is better? by BillKSmith (Monsignor) on Aug 09, 2012 at 02:50 UTC
Concatination is needed to break up a long line. `my $filename = $file_dir . "/filename1.log." . $today_date ;` [download]	[reply] [d/l]
Re: string concatenation, which way is better? by Anonymous Monk on Aug 09, 2012 at 00:35 UTC
In this case it probably makes little difference; it's a matter of personal preference. In the general case you sometimes need the exact-formatting control that sprintf() provides. Depends on the circumstances.	[reply]