Looping is a programming technique that repeats a set of instructions or displays output repeatedly until one or more conditions are met.

The first thing that we need to do it to query a database

This tag supports the following types of loops:

• cfloop: index loop
• cfloop: conditional loop
• cfloop: looping over a date or time range
• cfloop: looping over a query
• cfloop: looping over a list, a file, or an array

cfloop: index loop

An index loop repeats for a number of times that is determined by a numeric value. An index loop is also known as a FOR loop.

Syntax

<cfloop index = "parameter name" from = "beginning value" to = "ending value" step = "increment">HTML or CFML code ...</cfloop>

Example
The loop index is #LoopCount#.

cfloop: conditional loop

A conditional loop iterates over a set of instructions as long as a condition is True. To use this type of loop correctly, the instructions must change the condition every time the loop iterates, until the condition is False. Conditional loops are known as WHILE loops, as in, "loop WHILE this condition is true."

Syntax

<cfloop condition="expression">...</cfloop>

Example
The following example increments CountVar from 1 to 5.

<cfloop condition = "CountVar LESS THAN OR EQUAL TO 5"><cfset countvar =" CountVar">The loop index is <cfoutput>#CountVar#</cfoutput>.</cfloop>

cfloop: looping over a date or time range

Loops over the date or time range specified by the from and to attributes. By default, the step is 1 day, but you can change the step by creating a timespan. The cfloop tag loops over tags that cannot be used within a cfoutput tag.

Syntax

<cfloop from = "start time" to = "end time" index = "current value" step = "increment"></cfloop>

Example

The following example loops from today's date to today's date plus 30 days, stepping by 7 days at a time and displaying the date:

cfset startDate = Now()><cfset enddate =" Now()"><cfloop from="#startDate#" to="#endDate#" index="i" step="#CreateTimeSpan(7,0,0,0)#"><cfoutput>#dateformat(i, "mm/dd/yyyy")#</cfoutput></cfloop>

cfloop: looping over a query

A loop over a query executes for each record in a query record set. The results are similar to those of the cfoutput tag. During each iteration, the columns of the current row are available for output. The cfloop tag loops over tags that cannot be used within a cfoutput tag.

Syntax

<cfloop query = "query name" startrow = "row number" endrow = "row number"></cfloop>

Example

<cfquery name = "MessageRecords" datasource = "cfdocexamples">SELECT * FROM Messages</cfquery><cfloop query = "MessageRecords"><br /><cfoutput>#Message_ID#</cfoutput></cfloop>

cfloop: looping over a list, a file, or an array

Looping over a list steps through elements contained in any of these entities:

A variable
A value that is returned from an expression
An array
A file
Looping over a file does not open the entire file in memory.

Syntax

<cfloop index = "index name" array = "array" characters = "number of characters" delimiters = "item delimiter" file = "absolute path and filename">list = "list items" ...

Example

This loop displays four names:
<cfloop index = "ListElement" list = "John,Paul,George,Ringo"><cfoutput>#ListElement#</cfoutput>

You can put more than one character in the delimiters attribute, in any order. For example, this loop processes commas, colons, and slashes as list delimiters:

<cfloop index = "ListElement" list = "John/Paul,George::Ringo" delimiters = ",:/"><cfoutput>#ListElement#</cfoutput></cfloop>

ColdFusion skips the second and subsequent consecutive delimiters between list elements. Thus, in the example, the two colons between "George" and "Ringo" are processed as one delimiter.

To loop over each line of a file, use the tag as follows:

<cfloop file="c: empsimplefile.txt" index="line"><br /><cfoutput>#line#</cfoutput></cfloop>

To read a specified number of characters from a text file during each iteration of the loop, use the tag as follows:

<cfloop file="c:/tempsimplefile.txt" index="chars" characters="12"><cfoutput>#chars#</cfoutput></cfloop>

To loop over an array, you can do the following:

<cfset x =" ["><cfloop array="#x#" index="name"><cfoutput>#name#</cfoutput></cfloop>

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This is probably obvious to most of you out there but, just in case you missed it there is a setting in the CF Admin panel that will help keep your cfclasses directory from getting huge.

On the "Caching" page of CF Admin there is a checkbox titled "Save class files" if you are in development you should seriously keep that UNCHECKED.

Here's an example to illustrate why that is a good idea. We are working on a semi-complicated CF app using Model-Glue and Coldspring. When the site is first hit, after starting CF server, 3,002 .class files are generated and placed in the cfclasses directory. Now, imagine you are editing and revisiting some of those files (or flushing the entire MG cache). That number keeps on growing and growing. Eventually, something will go wrong and you'll want to delete some .class files to make sure you are seeing the latest code. However, because your cfclasses directory is so huge you won't even be able to "cd" into it. Your system will appear to hang. Trying to delete the directories contents will take a long, long time.

What do you do? Well you just uncheck that damn box. That will prevent a huge backlog of files from building up in the cfclasses directory in the first place.

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More Information visit ColdFusion Development Services.

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