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Posted by WildernessCat on 10/16/07 04:37
On Oct 15, 5:05 pm, Captain Paralytic <paul_laut...@yahoo.com> wrote:
> On 15 Oct, 14:43, WildernessCat <wilderness...@gmail.com> wrote:
>
>
>
> > On Oct 15, 3:17 pm, Captain Paralytic <paul_laut...@yahoo.com> wrote:
>
> > > On 15 Oct, 14:09, WildernessCat <wilderness...@gmail.com> wrote:
>
> > > > Hello there!
>
> > > > Suppose I have an associative array that looks like this:
> > > > $arr['alpha_1'] = 'some value';
> > > > $arr['alpha_3'] = 'some value';
> > > > $arr['alpha_4'] = 'some value';
> > > > $arr['beta_2'] = 'some value';
> > > > $arr['beta_4'] = 'some value';
> > > > $arr['beta_6'] = 'some value';
> > > > $arr['gamma_1'] = 'some value';
> > > > $arr['gamma_5'] = 'some value';
> > > > $arr['gamma_6'] = 'some value';
> > > > $arr['gamma_7'] = 'some value';
>
> > > > Let's assume that the array is reasonably large (hundreds of entries).
>
> > > > Is there an efficient way of getting all the items whose key starts
> > > > with 'beta'? (without doing a foreach/strncmp loop?)
>
> > > > Thanks in advance,
> > > > Danny
>
> > > Something like:
>
> > > preg_grep('/^beta/',array_keys($arr));
>
> > > should give you all the keys that start with 'beta'
>
> > Yes, it sure looks more compact in the code, but the question is
> > whether it's more efficient? I have a gut feeling that there is no
> > efficient way.
>
> > By the way I forgot to mention that the array is not sorted.- Hide quoted text -
>
> > - Show quoted text -
>
> The fact that it is not sorted shouldn't matter. As far as efficiency
> goes, it is all handled by a BIF as opposed to interpreted code, so it
> has the opportunity to be more efficient.
>
> Now, I don't know how you want to use the results but this leaves you
> with an array containing all the keys that you need for later use.
Thanks. I think I'll go with this one.
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