Welcome!

You will be redirected in 30 seconds or close now.

ColdFusion Authors: Yakov Fain, Jeremy Geelan, Maureen O'Gara, Nancy Y. Nee, Tad Anderson

Related Topics: ColdFusion

ColdFusion: Article

Making Decisions in Your Code with ColdFusion "cfif"

Before you can implement conditional logic in your code you have to understand what conditional logic is

This month I will examine the cfif tag and discuss how we can use that tag to make decisions in our code. Along the way I'll talk about Boolean logic, decision operators, and Boolean operators in CFML.

Understanding Conditional Logic
Before you can implement conditional logic in your code you have to understand what conditional logic is. I have no doubt that every one of you knows what conditional logic is, although you may never have heard it referred to as such. Conditional logic is just a fancy way of saying that you are going to make a decision. Usually the decision is based upon some sort of condition or the result of an operation.

You and I make decisions every day, so let's delve into some real-world examples. Suppose I'm driving a car and come to an intersection with another road. I need to make a decision whether to turn left, turn right, or continue straight on the main road. Each decision may have different consequences. If I turn right, I go to the bank. If I turn left, I go to the grocery store. Going straight might take me somewhere else, home, for example. Since it has been a long day, I want to go home. I'm going to drive straight. This is an example of conditional logic in practice. I made a choice to go straight, based on a condition, I want to go home, and something happened as a result of that condition.

Making decisions about groceries and the bank is all well and good, but how does this apply to Web development? I'm glad you asked. Suppose you have a sign-up form on your Web site. Your users enter some account information, such as an e-mail address, their name, a username, and password. You take that information and create a user account in your database.

What happens if the user does not enter a username? Can you still create the account? How do you handle that situation? You can use conditional logic to make sure that the username is not left blank. Suppose a user looks at the shopping cart before adding items to it? You can use conditional logic to display an "empty cart" message. Suppose a user enters a birth date as November 15, 2050? You get the idea - we can use conditional logic in our code to solve these types of problems.

The Format of the cfif Tag
In CFML, you can use the cfif tag to perform conditional logic statements. It comes in this format:

<cfif expression>
Perform Actions
</cfif>

The cfif tag is an oddball tag in the CFML language. Unlike most tags, it doesn't take any explicit parameter name and value arguments; it is simply followed by an expression after the tag name. A review of expressions can be found in last month's article; or you can go straight to the source: http://livedocs.macromedia.com/coldfusion/6.1/htmldocs/cfml_b14.htm. The CFML interpreter uses an expression to determine whether or not to process data. Expressions are literal values, variables, or functions (which return a Boolean value).

The expression inside the cfif tag must evaluate to a Boolean value (a true/false). Boolean values are represented as either "true" or "false", "yes" or "no", or "0" or any number. If the expression evaluates to true, then the action immediately following the <cfif> is performed. If the expression evaluates to false, then the action is not performed and template execution will continue after the end cfif tag. There are two types of operators that are used with cfif tags: decision operators and Boolean operators. Both evaluate to Boolean values.

Decision and Boolean Operators
The two types of operators used in a cfif expression are decision operators and Boolean operators. Boolean operators refer to specific operators from Boolean algebra. Decision operators are used for comparisons. This is a list of the Boolean and decision operators supported in CFML:

  • NOT: A Boolean operator that returns the opposite of the specified expressions. If you want the NOT of true, then you get false. The NOT of false is true.
  • AND: A Boolean operator that returns true if both operands are true, but false otherwise.
  • OR: A Boolean operator that returns true if at least one of the operands is true, but returns false otherwise.
  • XOR: A Boolean operator that performs an exclusive or. If only one of the values is true, then the result is true. Otherwise the result is false.
  • EQV: A Boolean operator that performs equivalence. Returns true if both operands are true or both operands are false. Returns false if the operands are different.
  • IMP: A Boolean operator that performs implication. It is akin to the logical statement "If condition 1, then condition 2." This returns false if condition 1 is true and condition 2 is false. True is returned in all other cases.
  • IS, EQUAL, EQ: Decision operators that test for two values being equal. If the first value is equal to the second value, the final result is true.
  • IS NOT, NOT EQUAL, NEQ: Decision operators that test for two values not being equal. If the two values are equal, then the final result will be false.
  • GREATER THAN, GT: Decision operators that are used to check if the first value is greater than the second value.
  • GREATER THAN OR EQUAL TO, GTE, GE: Decision operators that check to see if the first value is larger than or equal to the second value.
  • LESS THAN, LT: Decision operators that are used to check if the first value is smaller than the second value.
  • LESS THAN OR EQUAL TO, LTE, LE: Decision operators that check to see if the first value is smaller than or equal to the second value.
  • CONTAINS: A decision operator that returns true if the value on the left contains the value on the right.
  • DOES NOT CONTAIN: A decision operator that returns true if the value on the left does not contain the value on the right.

You can read more about decision operators in the Macromedia Livedocs at http://livedocs.macromedia.com/coldfusion/6.1/htmldocs/expresa6.htm and about Boolean operators at http://livedocs.macromedia.com/coldfusion/6.1/htmldocs/expresa5.htm.

It is worth noting the order in which these operations are applied. This builds right off the order of operations I discussed in last month's article. First, the arithmetic operators are applied, and then the string operator is applied. Following that, the decision operators are applied: EQ, NEQ, LT, LTE, GT, GTE, CONTAINS, DOES NOT CONTAIN from left to right in the order that they appear. Then come the Boolean operators. First the NOT operator is applied, then the AND operator. Then the OR operator, followed by the XOR operator. Next comes EQV, and finally, IMP. You can always use parentheses to change the order of operations. In fact, when in doubt, use parentheses to force the order of operations! In most cases you won't be mixing arithmetic or string operands with decision or Boolean ones; however, decision and Boolean operands are often used together. Let me show you how to put this into practice.

Take Some Code for a Test Drive
Suppose you want to make a simple interface for users to choose which way to turn their car. This sample uses an HTML form to collect the user input, as shown below. If you are unfamiliar with HTML forms, I found some great Web-based tutorials located at www.weballey.net/forms and www.wdvl.com/Authoring/Scripting/Tutorial/html_forms_intro.html.

<form action="Go.cfm" method="post">
<input type="Radio" name="Route" value="Right">Right
<input type="Radio" name="Route" value="Left">Left
<input type="Radio" name="Route" value="Straight">Straight<Br>
<input type="submit">
</form>

The form uses radio buttons to let the user select a direction and then click Submit to see the result page:

<cfif Route is "Right">
Go to Bank<br>
</cfif>
<cfif Route is "Left">
Go to Store<br>
</cfif>
<cfif Route is "Straight">
Go Home<br>
</cfif>

If you copy this code to see the example in action, make sure that you put it in a file named go.cfm and put both files in the same directory. This code uses the decision operator IS to determine the value of Route. It uses multiple cfif tags to figure out the value of the Route variable and what it should be.

Specifying Additional Conditions with cfelse and cfelseif
Up to this point the cfif tags have performed actions only if an expression resulted to true. What happens when you need to perform some actions when a condition is false? Well, you could use the NOT operator to create a second cfif statement, but there is a better way. CFML offers us the <cfelse> tag. This is the syntax:

<cfif expression>
Perform Actions
<cfelse>
Perform Other Actions
</cfif>

The cfif tag remains the same, as do the actions that we perform if the condition is true. What changes is that we have a cfelse tag. The cfelse tag does not take any parameters or expressions - it simply offers the alternative code to run in case a cfif evaluates to false.

If you go back to the driving example, you will see that we have three separate conditions. Turning left directs us to the grocery store, turning right takes us to the bank, and going straight sends us home. In this case, it won't be possible to perform all of the actions at once. Our first example is inefficient because we evaluate all conditions even after finding the correct one.

There is a better way to handle this situation - through the use of a tag called cfelseif. The cfelseif tag allows us to add multiple conditions to our cfif statement. If the first condition does not evaluate to true, then the second cfelseif condition is evaluated. If the second is not true, then the third is evaluated. Use of the cfelseif is optional, and there is no limit to the number of cfelseif conditions you can have. By contrast, the cfelse tag can be used only once. This is the syntax for cfelseif:

<cfif expression>
Perform Actions
<cfelseif expression2>
Perform Other Actions
</cfif>

The code is very similar to the previous sample. The cfelseif tag contains an additional expression, whereas the cfelse did not. It will be evaluated only if the cfif expression is false. When there are cfelseif tags and a cfelse tag, the cfelse tag must always come last (after all cfelseif tags). The previous example used multiple cfif tags. The cfelseif tag lets us combine the separate cfif tags into a single login. This is the code:

<cfif Route is "Right">
Go to Bank<br>
<cfelseif Route is "Left">
Go to Store<br>
<cfelse>
Go Home<br>
</cfif>

If the route chosen is right, then we go to the bank. If the route is left we go to the store. If nothing else, we continue to go straight on home.

Where Do I Go from Here?
The cfif statement can get very complicated if you start using one cfif statement inside another cfif statement. If you want to do some independent study, I would suggest reading up on cfswitch at http://livedocs.macromedia.com/coldfusion/ 6.1/htmldocs/tags-c10.htm#wp1103819 and cfcase at http://livedocs.macromedia.com/coldfusion/ 6.1/htmldocs/tags-pa9.htm#wp2664410. They are used together to form case statements, which are a different form of conditionals that you can use in your code. The use of cfswitch and cfcase statements is often a great way to simplify complex cfif.

It has been a pleasure writing these articles for you, and I'm pleased to announce that I've received my first topic request. Next month I will be writing about structures and arrays. Keep the ideas coming!

More Stories By Jeffry Houser

Jeffry is a technical entrepreneur with over 10 years of making the web work for you. Lately Jeffry has been cooped up in his cave building the first in a line of easy to use interface components for Flex Developers at www.flextras.com . He has a Computer Science degree from the days before business met the Internet and owns DotComIt, an Adobe Solutions Partner specializing in Rich Internet Applications. Jeffry is an Adobe Community Expert and produces The Flex Show, a podcast that includes expert interviews and screencast tutorials. Jeffry is also co-manager of the Hartford CT Adobe User Group, author of three ColdFusion books and over 30 articles, and has spoken at various events all over the US. In his spare time he is a musician, old school adventure game aficionado, and recording engineer. He also owns a Wii. You can read his blog at www.jeffryhouser.com, check out his podcast at www.theflexshow.com or check out his company at www.dot-com-it.com.

Comments (7) View Comments

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.


Most Recent Comments
CFDJ News Desk 12/04/05 02:00:18 AM EST

Making Decisions in Your Code with ColdFusion "cfif". This month I will examine the cfif tag and discuss how we can use that tag to make decisions in our code. Along the way I'll talk about Boolean logic, decision operators, and Boolean operators in CFML.

SYS-CON Canada News Desk 12/03/05 11:19:15 AM EST

Making Decisions in Your Code with "cfif" This month I will examine the cfif tag and discuss how we can use that tag to make decisions in our code. Along the way I'll talk about Boolean logic, decision operators, and Boolean operators in CFML.

CFDJ News Desk 12/03/05 10:50:59 AM EST

Making Decisions in Your Code with "cfif"
This month I will examine the cfif tag and discuss how we can use that tag to make decisions in our code. Along the way I'll talk about Boolean logic, decision operators, and Boolean operators in CFML.

Jeff Houser 11/14/05 12:35:24 PM EST

Hi Kevin,
I just saw your comment now. I'm glad you like the articles.

The type of security I wrote about in the "Remember Me" article (August 2004) is still what I use today. I find that, in most cases, the web applications I've worked on did not need anything more advanced than that.

I dealt with Lotus Notes a lot right out of college (a while ago) and their security scheme is the most powerful/flexible I've ever seen.

In my first book, (Instant Coldfusion now extremely dated), I wrote about implementing this sort of system in CF, but it is overkill for most web apps.

I'll keep a "Back to basics" article in mind, although these days I try to tie in with the issue focus.

Jeff Houser 11/14/05 12:34:57 PM EST

Hi Kevin,
I just saw your comment now. I'm glad you like the articles.

The type of security I wrote about in the "Remember Me" article (August 2004) is still what I use today. I find that, in most cases, the web applications I've worked on did not need anything more advanced than that.

I dealt with Lotus Notes a lot right out of college (a while ago) and their security scheme is the most powerful/flexible I've ever seen.

In my first book, (Instant Coldfusion now extremely dated), I wrote about implementing this sort of system in CF, but it is overkill for most web apps.

I'll keep a "Back to basics" article in mind, although these days I try to tie in with the issue focus.

CFDJ News Desk 10/20/05 09:51:59 PM EDT

ColdFusion Developer's Journal - Making Decisions in Your Code with "cfif" This month I will examine the cfif tag and discuss how we can use that tag to make decisions in our code. Along the way I'll talk about Boolean logic, decision operators, and Boolean operators in CFML.

Kevin 10/20/05 09:25:55 PM EDT

I like your articles quite a bit!

I was wondering what your current take on home-spun user security is now that we are almost in 2006 and your article about remembering user logins was 2004 if I remember correctly...

Have you got any thoughts on more complex role based models vs privilage based? etc...

I'd like to here your thoughst on this.

Also, it's old news, but I download applications from what i would have though to be good cfml-ers that still use #'s where the should not! a nice back to basics article might be good for specificly when to use and not use #'s

thanks!

Kevin

@ThingsExpo Stories
Bert Loomis was a visionary. This general session will highlight how Bert Loomis and people like him inspire us to build great things with small inventions. In their general session at 19th Cloud Expo, Harold Hannon, Architect at IBM Bluemix, and Michael O'Neill, Strategic Business Development at Nvidia, discussed the accelerating pace of AI development and how IBM Cloud and NVIDIA are partnering to bring AI capabilities to "every day," on-demand. They also reviewed two "free infrastructure" pr...
More and more brands have jumped on the IoT bandwagon. We have an excess of wearables – activity trackers, smartwatches, smart glasses and sneakers, and more that track seemingly endless datapoints. However, most consumers have no idea what “IoT” means. Creating more wearables that track data shouldn't be the aim of brands; delivering meaningful, tangible relevance to their users should be. We're in a period in which the IoT pendulum is still swinging. Initially, it swung toward "smart for smart...
SYS-CON Events announced today that SoftLayer, an IBM Company, has been named “Gold Sponsor” of SYS-CON's 18th Cloud Expo, which will take place on June 7-9, 2016, at the Javits Center in New York, New York. SoftLayer, an IBM Company, provides cloud infrastructure as a service from a growing number of data centers and network points of presence around the world. SoftLayer’s customers range from Web startups to global enterprises.
20th Cloud Expo, taking place June 6-8, 2017, at the Javits Center in New York City, NY, will feature technical sessions from a rock star conference faculty and the leading industry players in the world. Cloud computing is now being embraced by a majority of enterprises of all sizes. Yesterday's debate about public vs. private has transformed into the reality of hybrid cloud: a recent survey shows that 74% of enterprises have a hybrid cloud strategy.
20th Cloud Expo, taking place June 6-8, 2017, at the Javits Center in New York City, NY, will feature technical sessions from a rock star conference faculty and the leading industry players in the world. Cloud computing is now being embraced by a majority of enterprises of all sizes. Yesterday's debate about public vs. private has transformed into the reality of hybrid cloud: a recent survey shows that 74% of enterprises have a hybrid cloud strategy.
In his General Session at 17th Cloud Expo, Bruce Swann, Senior Product Marketing Manager for Adobe Campaign, explored the key ingredients of cross-channel marketing in a digital world. Learn how the Adobe Marketing Cloud can help marketers embrace opportunities for personalized, relevant and real-time customer engagement across offline (direct mail, point of sale, call center) and digital (email, website, SMS, mobile apps, social networks, connected objects).
SYS-CON Events announced today that Tintri, Inc, a leading provider of enterprise cloud infrastructure, will exhibit at SYS-CON's 20th International Cloud Expo®, which will take place on June 6-8, 2017, at the Javits Center in New York City, NY. Tintri offers an enterprise cloud platform built with public cloud-like web services and RESTful APIs. Organizations use Tintri all-flash storage with scale-out and automation as a foundation for their own clouds – to build agile development environments...
Have you ever noticed how some IT people seem to lead successful, rewarding, and satisfying lives and careers, while others struggle? IT author and speaker Don Crawley uncovered the five principles that successful IT people use to build satisfying lives and careers and he shares them in this fast-paced, thought-provoking webinar. You'll learn the importance of striking a balance with technical skills and people skills, challenge your pre-existing ideas about IT customer service, and gain new in...
SYS-CON Events announced today that Outlyer, a monitoring service for DevOps and operations teams, has been named “Bronze Sponsor” of SYS-CON's 20th International Cloud Expo®, which will take place on June 6-8, 2017, at the Javits Center in New York City, NY. Outlyer is a monitoring service for DevOps and Operations teams running Cloud, SaaS, Microservices and IoT deployments. Designed for today's dynamic environments that need beyond cloud-scale monitoring, we make monitoring effortless so you...
SYS-CON Events announced today that Outlyer, a monitoring service for DevOps and operations teams, has been named “Bronze Sponsor” of SYS-CON's 20th International Cloud Expo®, which will take place on June 6-8, 2017, at the Javits Center in New York City, NY. Outlyer is a monitoring service for DevOps and Operations teams running Cloud, SaaS, Microservices and IoT deployments. Designed for today's dynamic environments that need beyond cloud-scale monitoring, we make monitoring effortless so you ...
SYS-CON Events announced today that CA Technologies has been named “Platinum Sponsor” of SYS-CON's 20th International Cloud Expo®, which will take place on June 6-8, 2017, at the Javits Center in New York City, NY, and the 21st International Cloud Expo®, which will take place October 31-November 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. CA Technologies helps customers succeed in a future where every business – from apparel to energy – is being rewritten by software. From ...
Why do your mobile transformations need to happen today? Mobile is the strategy that enterprise transformation centers on to drive customer engagement. In his general session at @ThingsExpo, Roger Woods, Director, Mobile Product & Strategy – Adobe Marketing Cloud, covered key IoT and mobile trends that are forcing mobile transformation, key components of a solid mobile strategy and explored how brands are effectively driving mobile change throughout the enterprise.
SYS-CON Events announced today that Technologic Systems Inc., an embedded systems solutions company, will exhibit at SYS-CON's @ThingsExpo, which will take place on June 6-8, 2017, at the Javits Center in New York City, NY. Technologic Systems is an embedded systems company with headquarters in Fountain Hills, Arizona. They have been in business for 32 years, helping more than 8,000 OEM customers and building over a hundred COTS products that have never been discontinued. Technologic Systems’ pr...
Artificial Intelligence has become a topic of intense interest throughout the cloud developer and enterprise IT communities. Accordingly, attendees at the upcoming Cloud Expo | @ThingsExpo at the Javits Center in New York, June 6-8, will find fresh new content in a new track called Cognitive Computing | Artificial Intelligence, Machine Learning, Deep Learning. Cloud Expo is still accepting submissions for this new track, so please visit www.cloudcomputingexpo.com for the latest information. 2...
SYS-CON Events announced today that CA Technologies has been named “Platinum Sponsor” of SYS-CON's 20th International Cloud Expo®, which will take place on June 6-8, 2017, at the Javits Center in New York City, NY, and the 21st International Cloud Expo®, which will take place October 31-November 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. CA Technologies helps customers succeed in a future where every business – from apparel to energy – is being rewritten by software. From ...
Buzzword alert: Microservices and IoT at a DevOps conference? What could possibly go wrong? In this Power Panel at DevOps Summit, moderated by Jason Bloomberg, the leading expert on architecting agility for the enterprise and president of Intellyx, panelists peeled away the buzz and discuss the important architectural principles behind implementing IoT solutions for the enterprise. As remote IoT devices and sensors become increasingly intelligent, they become part of our distributed cloud enviro...
SYS-CON Events announced today that Hitrons Solutions will exhibit at the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Hitrons Solutions Inc. is distributor in the North American market for unique products and services of small and medium-size businesses, including cloud services and solutions, SEO marketing platforms, and mobile applications.
"I think that everyone recognizes that for IoT to really realize its full potential and value that it is about creating ecosystems and marketplaces and that no single vendor is able to support what is required," explained Esmeralda Swartz, VP, Marketing Enterprise and Cloud at Ericsson, in this SYS-CON.tv interview at @ThingsExpo, held June 7-9, 2016, at the Javits Center in New York City, NY.
SYS-CON Events announced today that TMC has been named “Media Sponsor” of SYS-CON's 20th International Cloud Expo and Big Data at Cloud Expo, which will take place on June 6–8, 2017, at the Javits Center in New York City, NY, , and the 21st International Cloud Expo, which will take place October 31-November 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Global buyers rely on TMC’s content-driven marketplaces to make purchase decisions and navigate markets. Learn how we can he...
In his session at @ThingsExpo, Steve Wilkes, CTO and founder of Striim, will delve into four enterprise-scale, business-critical case studies where streaming analytics serves as the key to enabling real-time data integration and right-time insights in hybrid cloud, IoT, and fog computing environments. As part of this discussion, he will also present a demo based on its partnership with Fujitsu, highlighting their technologies in a healthcare IoT use-case. The demo showcases the tracking of patie...