Rob Dixon wrote:
> John W. Krahn wrote:
>>
>> Gauthier, Dave wrote:
>>>
>>> Getting unwanted list elements when using split with regex. Here's an
>>> example....
>>>
>>> $str = "abc=In";
>>> @arr = split(/[a-zA-Z0-9]/,$str);
>>> foreach $a (@arr)
>>> {print "$a\n";}
>>>
>>> I get...
>>>
>>> <> <> <> <=>
^ ^ ^ ^
O T T F
n w h o
e o r u
e r
e
>>> If I change "abc=In" to "abcdef=In", I get 6 unwanetd null elements (one
>>> per char before the "="). I was expectiing a single element list
>>> with arr[0] = "=".
>>>
>>> What's Up ? Is ther a clen way to prevent creating these unwanted
>>> elements?
>>
>> In your example the string "abc=In" is being split using the expression
>> /[a-zA-Z0-9]/. That expression matches in the string at positions 0,
>> 1, 2, 4
>> and 5 therefore split will produce a list of *six* elements:
>>
>> $ perl -le'
>> $str = "abc=In";
>> print ++$x, ": <$_>" for split /[a-zA-Z0-9]/, $str, -1;
>> '
>> 1: <>
>> 2: <>
>> 3: <>
>> 4: <=>
>> 5: <>
>> 6: <>
>>
>> Your example only shows four because split automatically discards any
>> trailing
>> empty elements.
>
> [snip]
>
> Er, but he shows /six/ elements; and split /doesn't/ discard trailing empty
> elements. Or am I misunderstanding you John?
perldoc -f split
split /PATTERN/,EXPR,LIMIT
split /PATTERN/,EXPR
split /PATTERN/
split Splits the string EXPR into a list of strings and returns that
list. By default, empty leading fields are preserved, and empty
trailing ones are deleted. (If all fields are empty, they are
considered to be trailing.)
John
--
Perl isn't a toolbox, but a small machine shop where you can special-order
certain sorts of tools at low cost and in short order. -- Larry Wall
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