来自perlmonk的怪问题！

POLOGG

1. use strict;
   
2. #use warnings;
   
3. 
   
4. for my $i (1 .. 20)
   
5. {
   
6.     isodd( $i );
   
7.     print "$i\n";
   
8. }
   
9. 
   
10. sub isodd
    
11. {
    
12.     my $i = shift;
    
13.     next if int( $i / 2 ) * 2 == $i;
    
14.     return;
    
15. }

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这段代码没有使用warnings

注意在sub中使用的next，应该是在for中起了作用！

flw

我觉得这应该算是一个 BUG 了，不知道 Perl 官方怎么认为？

yzhkp

freebsd6下perl5.8.8运行结果：
1
Exiting subroutine via next at test.pl line 14.
3
Exiting subroutine via next at test.pl line 14.
5
Exiting subroutine via next at test.pl line 14.
7
Exiting subroutine via next at test.pl line 14.
9
Exiting subroutine via next at test.pl line 14.
11
Exiting subroutine via next at test.pl line 14.
13
Exiting subroutine via next at test.pl line 14.
15
Exiting subroutine via next at test.pl line 14.
17
Exiting subroutine via next at test.pl line 14.
19
Exiting subroutine via next at test.pl line 14.

POLOGG

原帖由 yzhkp 于 2006-3-31 10:54 发表
freebsd6下perl5.8.8运行结果：
1
Exiting subroutine via next at test.pl line 14.
3
Exiting subroutine via next at test.pl line 14.
5
Exiting subroutine via next at test.pl line 14.
7
Exiting ...

这段应该是有warings的情况下的吧！

ulmer

原帖由 POLOGG 于 2006-3-30 20:03 发表
use strict;
#use warnings;

for my $i (1 .. 20)
{
    isodd( $i );
    print "$i\n";
}

sub isodd
{
    my $i = shift;
    next if int( $i / 2 ) * 2 == $i;
    return;
...

Such code should be improved. The idea that uses "next" in sub and put this sub isodd()
in for loop. It seems "next" used in a loop, but the program's style (or logical) is not good.
How can I use it as standlone without a loop and switch "use warning" on?

Usually using good English as what meas in Perl style. Such as isFoo(), existsFoo() returns
generally boolean value: 1 or 0

Resolution maybe:
1. use warning but put "no warnings;" in sub isodd {..}.   
2. I prefer to rewrite sub isodd:

1. 
   
2. use strict;
   
3. use warnings;
   
4. sub is_odd {
   
5.     my $i = shift;
   
6.     return  int($i/2) * 2 == $i ? 0 : 1;
   
7. }
   
8. for (1..20) {
   
9.     print "$_; " if is_odd($_);
   
10. }
    
11. 
    

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Just 4 Fun, ulmer

-----------------------------------
Practice,practice makes perfect.

[ 本帖最后由 ulmer 于 2006-3-31 15:44 编辑 ]

POLOGG

原帖由 ulmer 于 2006-3-31 15:42 发表


Such code should be improved. The idea that uses "next" in sub and put this sub isodd()
in for loop. It seems "next" used in a loop, but the program's style (or logical) is ...

nice！