one or two liners apprecaited!

[laredotornado]

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";

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

Any short cuts are greatly appreciated.

Thanks, - Dave

[Oli Filth]

la***********@zipmail.com said the following on 11/05/2006 15:32:

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";

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

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]

la***********@zipmail.com wrote:

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";

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

Any short cuts are greatly appreciated.

Thanks, - Dave

This one-liner should work:

print implode(",", array_diff(explode(",", $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.