Re: Help with perl syntax

merlyn has lead you to the best way to do this, namely constructing a regex that looks for the beginning of a line, zero or more whitespace characters, the octothorpe, and absolutely no exclamation point.

Your double-regex check would work if you put multiple conditions in your if or unless statements. It's not the best option in this case, but it will work in other situations:

next READ if (/^\s*#/ and !(/^\s*#!/));

With the and (or &&), both conditions have to be true. The second is negated (with the leading !), so it achieves the same thing as the single regex.

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RE: Re: Help with perl syntax by zzspectrez (Hermit) on Oct 29, 2000 at 03:33 UTC
merlyn's solution is the better way to do it, I agree. I like your solution as well, I didnt think of using negation within the if construct. More than anything, I was just trying to figure out how perl would handle me combining if and unless within one statement. Like I did with: `unless (/^#!/) {next READ if (/^\s#/)};` [download] And how although that works the following does not work and perl proceeds to give an error: `if (/^\s#/) { next READ } unless (/^#!/);` [download] By looking at perl code from others I have seen how perl is flexible in how you structure things. You are not forced into a specific way of doing it such as the following. `if (/^\s#/) { next READ }` [download] Can be easily written: `next READ if (/^\s#/);` [download] I'm still unsure of how perl will handle certain structures. For example I would have coded the above example the first way thinking perl would of complained about the structure of the second. THANKS! zzspectrez	[reply] [d/l] [select]

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RE: Re: Help with perl syntax
by zzspectrez (Hermit) on Oct 29, 2000 at 03:33 UTC

merlyn's solution is the better way to do it, I agree.

I like your solution as well, I didnt think of using negation within the if construct.

More than anything, I was just trying to figure out how perl would handle me combining if and unless within one statement.
Like I did with:

unless (/^#!/) {next READ if (/^\s*#/)};
[download]

And how although that works the following does not work and perl proceeds to give an error:

if (/^\s*#/) { next READ } unless (/^#!/);
[download]

By looking at perl code from others I have seen how perl is flexible in how you structure things. You are not forced into a specific way of doing it such as the following.

if (/^\s*#/) {
  next READ
}
[download]

Can be easily written:

next READ if (/^\s*#/);
[download]

I'm still unsure of how perl will handle certain structures. For example I would have coded the above example the first way thinking perl would of complained about the structure of the second.

THANKS!
zzspectrez

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