seaching a list

[Charisma Bypass]

What would be the best way to search thru a list of stuff and say "got it" or "not", assuming no database involved?

Imagine a list of (let's say) towns and villages in the UK, there's thousands of them!  I need a search facility so that any can search for (let's say) Amblethorpe...and if I got it, it says "got it". Or not.

XML ? 

[Charisma Bypass]

Bumping this backup, as the project is now on.

So, a big long list in a .txt file. Best way to make it searchable?

There are about 51000 entries in the list.

[Jeep Stone]

If you can make it XML, then you can use XSLT to match against nodes/attributes. You just need a little bit of javascript/PHP/whatever you like to perform the transform

[JasonD]

51000 is nothing. Even a dumb read line by line will take no time at all.

Code:

function haveTown($town)
{
    $got = false;
    $fp = fopen('not-so-big-list-o-stuff.txt', 'rb');
    while ($line = trim(fgets($fp))) {
        if ($line == $town) {
            $got = true;
            break;
        }
    }
    fclose($fp);
    return $got;
}

[Charisma Bypass]

Cheers Guys.  Appreciate the time.

Jason, is 51000 entries -seriously- not going to impact the performance of a search?

[JasonD]

I'd guesstimate (on past performance) the above will take < 0.05 seconds to read to the bottom of the list, assuming it didn't match eariler.

I had a discussion with someone about similar code a few years back with benchmarks and such and we concluded anything under 300,000 lines wasn't worth the effort of doing any different.

You could optimise it further one of two ways, since the further down the list you go the longer it takes sort the list in order of popularity, but I don't have any clever ways to determine that.

Or by sorting the list alphabetically and adding

Code:

if ($line > $town) {
     break;
}

Then if Abingdon isn't on the list it will stop at Accrington instead of reading to York.

If you want more then have some precomputed points for the first entry for the inital letter and fseek to it.

But seriously, any more complexity that that you might as well put it in a database.

[Charisma Bypass]

Many thanks