Searching Arrays For Elements

05/12/2007 | ColdFusion | 10 Comments

Through open source, co workers and other just asking for help I get to see a lot of other peoples code. I believe it is a great learning tool that every developer should utilize. I know that if someone were to look at my code they could easily critique so please do not take this article the wrong way. One thing I see over and over is looping over an array to search for a specific value. I think that converting this array to a list provides a clear path to search the list using the listFind() method. Here is what I see a lot of and curious why you would search an array this way.

view plain print about

1<cfset states = ["Ohio","Michigan","California","Indiana","Florida"]>
2
3    <cfloop from="1" to="#arrayLen(states)#" index="x">
4        <cfif states[x] EQ "Ohio">
5            Ohio Found!<br>
6        <cfelse>
7            <cfoutput>#states[x]#</cfoutput><br>
8        </cfif>
9    </cfloop>

The code above will run fine when executed I just do not see it as a clear solution. While this example is not the best it does provide some code. Also the example uses Scorpio Implicit array creation so dont let that throw you off.

view plain print about

1<cfset states = ["Ohio","Michigan","California","Indiana","Florida"]>
2
3    <cfif listFind(arrayToList(states),"Ohio")>
4        Ohio Found!
5    </cfif>

I am curious to find out others thoughts on this. This is how I have always searched an array and found it cleaner that looping an array.

This entry was posted on May 12, 2007 at 5:32 PM and has received 1592 views. Comments 10 | Print this entry.

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#1 by Jason Holden on 5/12/07 - 6:29 PM

I like the shorter syntax in example 2!
#2 by zac spitzer on 5/13/07 - 12:12 AM

I usually convert the list to a struct and using structkeyexists... if you are doing it as a once off it there's not much difference, but if you are going to be searching the same list often it rocks...

creating a struct like my_struct[q_table.pk_id]=q_table.currentrow is quite handy as well
#3 by PaulH on 5/13/07 - 5:08 AM

as far as i can tell there's no real speed gain using ListFind() vs simply looping over the states array. while you write less code w/the ListFind() technique i think it's a bit harder to understand at first glance. in any case, ListFind() is case sensitive (the looping method isn't, at least on windows) so you'd need ListFindNoCase() *and* it won't work if you're searching for multiple values w/out some hoop jumping.

if there was a measurable speed difference i'd jump on this bandwagon but there's pitfalls to that approach & no real gain.
#4 by Lola LB on 5/13/07 - 7:07 AM

Actually, i disagree, PaulH. The 2nd example is a lot easier to read. Valid point about searching for multiple values, though.
#5 by Sammy Larbi on 5/13/07 - 10:00 AM

Well, I like the idea in the 2nd example, but you'd need to know in advance that none of your data items contain the delimiter. Depending on what you are storing and what you need it for, I like the idea of using a struct as the mechanism as well.
#6 by Dan on 5/13/07 - 11:39 AM

Maybe as always it just comes down to situation. I guess I can see a need for both now. I still think the 2nd is easier to read.

@Paul - Nice catch, the listFindNoCase is probably going to be used more!
#7 by Mark Mandel on 5/13/07 - 8:53 PM

You could also do:
states.contains("Ohio");
and hook into some Java goodness ;)
#8 by PaulH on 5/13/07 - 10:31 PM

now that's "readable", no need to parse the code & the meaning's not easily lost. but contains() is case-sensitive too.
#9 by Dan on 5/14/07 - 9:51 AM

Mark, Great tip. Anymore useful tips for tapping into Java?
#10 by Shaji on 5/14/07 - 11:57 PM

Dan,
More useful tips at http://coldfused.blogspot.com/2007/01/extend-cf-na...