Re: Foreach Loop Optimization

I don't see anything that would make that big of a difference. I think the problem is elsewhere.

time is a system call. You could save a little speed by calling it once outside the loop.
If /approv/i should actually checking for equality, lc($_) eq 'approv' is 122% faster when the check is true and 28% faster when the check is false.

Comments not related to performance:

$localtime = FormatTime($moduleField[2]) if $moduleField[2];
$localtime = "n/a" unless $moduleField[2];
[download]

could be written

$localtime = $moduleField[2] ? FormatTime($moduleField[2]) : "n/a";
[download]

Assigning to $_ is dangerous. And it's not even necessary here. Change

$_ = $headers[$dataCount];
if( /approv/i )
[download]

if( $headers[$dataCount] =~ /approv/i )
[download]

Comment on Re: Foreach Loop Optimization Select or Download Code

Replies are listed 'Best First'.
Re^2: Foreach Loop Optimization by upallnight (Sexton) on Aug 01, 2007 at 16:11 UTC
Thanks for your code suggestions! The code is not calling time in the loop, only formatting time value from the database. Unfortunately, I have to use `/approv/i` because it has to match approv in the string when the string could be anything. Is `$localtime = $moduleField[2] ? FormatTime($moduleField[2]) : "n/a";` more efficient than my two lines of code? I don't think changing $_ is dangerous. The perdoc does it a lot. For some reason, I was thinking `=~` would change the value of `$headers[$dataCount]`. Thanks for that code, I bet its faster than changing the value of $_. http://uan.no-ip.org	[reply] [d/l] [select]
Re^3: Foreach Loop Optimization by ikegami (Patriarch) on Aug 01, 2007 at 16:27 UTC
I don't think changing $_ is dangerous. The perdoc does it a lot. Sometimes it won't cause any problems. Sometime it creates hard to debug action-at-a-distance problems because it's common for code to rely on `$_` being left unchanged by the functions it calls. If you modify `$_`, `local`ize it. Of course, `local $_ = $val;` is buggy so `local _ = \$val;` or `for ($val)` should be used instead. Or better yet, just don't assign to `$_`. In this particular case, the only thing the assignment to `$_` does is obfuscate, so it's a bad idea regardless of all the problems and complexity I just mentioned. For some reason, I was thinking `=~` would change the value of `$headers[$dataCount]`.* All `=~` does is specify the operand for the following (`m//`, `s///`, `tr///`, etc) operator.	[reply] [d/l] [select]