If Statement

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

Why are brackets compulsory with an If statement even if it has only one line, unlike in C?

Perl -

if(a!=b)
{
  a = b;
}

C -
if(a!=b)
  a = b;
[download]

Comment on If Statement Download Code

Replies are listed 'Best First'.
•Re: If Statement by merlyn (Sage) on Nov 04, 2002 at 18:50 UTC
By rule #1 {grin}. "Larry said so." There's never a chance of the "dangling else" problem. The syntax would be ambiguous without it. I forget the exact case, but apparently it'd be hard to tell for certain Perl constructs whether it was a curly-expression or the block that belongs to the `if`, and then you wouldn't know where the end of the block was. Perl has the "backward if" that C doesn't have: `$simple_expression if $some_condition;` [download] -- Randal L. Schwartz, Perl hacker Be sure to read my standard disclaimer if this is a reply.	[reply] [d/l]
Re: •Re: If Statement by jdporter (Paladin) on Nov 05, 2002 at 17:46 UTC
3. # The syntax would be ambiguous without it. I forget the exact case,... It's like this: `if ( $foo ) if ( $bar ) quux(); else # ???` [download] Which `if` is that `else` supposed to go with?	[reply] [d/l] [select]
•Re: Re: •Re: If Statement by merlyn (Sage) on Nov 05, 2002 at 18:18 UTC
No, not the dangling-else problem. I already addressed that in "point 2". There's something that's in Perl that's not in C that would have made it hard to tell if there was a single expression or a block following. Maybe it's just the anonymous hash constructor, but back when braces were made mandatory, there was no anon-hash constructor, so I don't think that was it. -- Randal L. Schwartz, Perl hacker Be sure to read my standard disclaimer if this is a reply.	[reply]
Re^2: If Statement by Aristotle (Chancellor) on Nov 06, 2002 at 12:17 UTC
Re: point 3: Maybe that C doesn't have naked blocks? So would `if($cond) { $foo } $bar;` mean `if($cond) { $foo } $bar;` [download] or is it `if($cond) { { $foo; } $bar; }` [download] Makeshifts last the longest.	[reply] [d/l] [select]
•Re: Re^2: If Statement by merlyn (Sage) on Nov 06, 2002 at 18:42 UTC
No. C has naked block. Where do you think Perl got it? {grin} -- Randal L. Schwartz, Perl hacker Be sure to read my standard disclaimer if this is a reply.	[reply]
Re^4: If Statement by Aristotle (Chancellor) on Nov 06, 2002 at 19:57 UTC
Re: Re^4: If Statement by Baz (Friar) on Dec 30, 2003 at 19:50 UTC
Re: If Statement by kabel (Chaplain) on Nov 04, 2002 at 18:50 UTC
alternatives: `a = b if ($a != $b);` [download] `$a != $b and a = b;` [download] HTH	[reply] [d/l] [select]
•Re: Re: If Statement by merlyn (Sage) on Nov 04, 2002 at 18:52 UTC
`a = b if ($a != $b);` [download] No need for those parens. I think it looks better without it. -- Randal L. Schwartz, Perl hacker Be sure to read my standard disclaimer if this is a reply.	[reply] [d/l]
Re: If Statement by fruiture (Curate) on Nov 04, 2002 at 18:51 UTC
Because Perl is not C. `$a = $b if $a != $b; # or if you want to stick to the order if( ) then; $a != $b and $a = $b;` [download] -- http://fruiture.de	[reply] [d/l]
Re: If Statement by Enlil (Parson) on Nov 04, 2002 at 18:47 UTC
The Camel states in the C Traps section (first thing no less), that the curly brackets are required for both `if` and `while` blocks. -enlil	[reply] [d/l] [select]
Re: If Statement by defyance (Curate) on Nov 04, 2002 at 18:55 UTC
Would this not work without the brackets? `$a = $b if $a != $b;` [download] This is valid for such a simple operation according to the Pocket Ref. Infact, one of the first examples of control statments looks like so: `expr1 if expr2 ; expr1 foreach list ;` [download] Did I read this wrong? UPDATE:Guess I didn't read it wrong! -- Can't never could do anything, so give me and inch, I'll make it a mile.	[reply] [d/l] [select]

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