one or two liners apprecaited!

[laredotornado@zipmail.com]

Hi, I'm using PHP 4. I have two scalar variables, each containing
comma separated lists of numbers

$big_list = "1,2,3,4,5,6,7, 8";
$small_list = "5,4,6";

"$small_lis t" will always contain less elements than "$big_list" and
all of "$small_lis t"s numbers will be included in "$big_list" . I want
to get a variable that contains "$big_list" minus "$small_lis t". In
the above example, the resulting varaible would contain "1,2,3,7,8" .

Any short cuts are greatly appreciated.

Thanks, - Dave

[Oli Filth]

Re: one or two liners apprecaited!

laredotornado@z ipmail.com said the following on 11/05/2006 15:32:[color=blue]
> Hi, I'm using PHP 4. I have two scalar variables, each containing
> comma separated lists of numbers
>
> $big_list = "1,2,3,4,5,6,7, 8";
> $small_list = "5,4,6";
>
> "$small_lis t" will always contain less elements than "$big_list" and
> all of "$small_lis t"s numbers will be included in "$big_list" . I want
> to get a variable that contains "$big_list" minus "$small_lis t". In
> the above example, the resulting varaible would contain "1,2,3,7,8" .[/color]

It's easier to deal with arrays than strings, so convert your lists to
arrays using explode(). Then use some combination of the PHP
array-handling functions; array_diff() might do the job you're after.


--
Oli

[Ian Taylor]

Re: one or two liners apprecaited!

laredotornado@z ipmail.com wrote:[color=blue]
> Hi, I'm using PHP 4. I have two scalar variables, each containing
> comma separated lists of numbers
>
> $big_list = "1,2,3,4,5,6,7, 8";
> $small_list = "5,4,6";
>
> "$small_lis t" will always contain less elements than "$big_list" and
> all of "$small_lis t"s numbers will be included in "$big_list" . I want
> to get a variable that contains "$big_list" minus "$small_lis t". In
> the above example, the resulting varaible would contain "1,2,3,7,8" .
>
> Any short cuts are greatly appreciated.
>
> Thanks, - Dave
>[/color]

This one-liner should work:

print implode(",", array_diff(expl ode(",", $big_list), explode(",",
$small_list)));

However, if you're using it in code you (or someone else!) would need to
maintain in the future, it would be wise to expand it to increase
readability.