Click here to close now.




















Welcome!

You will be redirected in 30 seconds or close now.

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

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
WebRTC has had a real tough three or four years, and so have those working with it. Only a few short years ago, the development world were excited about WebRTC and proclaiming how awesome it was. You might have played with the technology a couple of years ago, only to find the extra infrastructure requirements were painful to implement and poorly documented. This probably left a bitter taste in your mouth, especially when things went wrong.
Too often with compelling new technologies market participants become overly enamored with that attractiveness of the technology and neglect underlying business drivers. This tendency, what some call the “newest shiny object syndrome,” is understandable given that virtually all of us are heavily engaged in technology. But it is also mistaken. Without concrete business cases driving its deployment, IoT, like many other technologies before it, will fade into obscurity.
The Internet of Things is in the early stages of mainstream deployment but it promises to unlock value and rapidly transform how organizations manage, operationalize, and monetize their assets. IoT is a complex structure of hardware, sensors, applications, analytics and devices that need to be able to communicate geographically and across all functions. Once the data is collected from numerous endpoints, the challenge then becomes converting it into actionable insight.
Consumer IoT applications provide data about the user that just doesn’t exist in traditional PC or mobile web applications. This rich data, or “context,” enables the highly personalized consumer experiences that characterize many consumer IoT apps. This same data is also providing brands with unprecedented insight into how their connected products are being used, while, at the same time, powering highly targeted engagement and marketing opportunities. In his session at @ThingsExpo, Nathan Treloar, President and COO of Bebaio, will explore examples of brands transforming their businesses by t...
With the Apple Watch making its way onto wrists all over the world, it’s only a matter of time before it becomes a staple in the workplace. In fact, Forrester reported that 68 percent of technology and business decision-makers characterize wearables as a top priority for 2015. Recognizing their business value early on, FinancialForce.com was the first to bring ERP to wearables, helping streamline communication across front and back office functions. In his session at @ThingsExpo, Kevin Roberts, GM of Platform at FinancialForce.com, will discuss the value of business applications on wearable ...
With the proliferation of connected devices underpinning new Internet of Things systems, Brandon Schulz, Director of Luxoft IoT – Retail, will be looking at the transformation of the retail customer experience in brick and mortar stores in his session at @ThingsExpo. Questions he will address include: Will beacons drop to the wayside like QR codes, or be a proximity-based profit driver? How will the customer experience change in stores of all types when everything can be instrumented and analyzed? As an area of investment, how might a retail company move towards an innovation methodolo...
The Internet of Things (IoT) is about the digitization of physical assets including sensors, devices, machines, gateways, and the network. It creates possibilities for significant value creation and new revenue generating business models via data democratization and ubiquitous analytics across IoT networks. The explosion of data in all forms in IoT requires a more robust and broader lens in order to enable smarter timely actions and better outcomes. Business operations become the key driver of IoT applications and projects. Business operations, IT, and data scientists need advanced analytics t...
While many app developers are comfortable building apps for the smartphone, there is a whole new world out there. In his session at @ThingsExpo, Narayan Sainaney, Co-founder and CTO of Mojio, will discuss how the business case for connected car apps is growing and, with open platform companies having already done the heavy lifting, there really is no barrier to entry.
Contrary to mainstream media attention, the multiple possibilities of how consumer IoT will transform our everyday lives aren’t the only angle of this headline-gaining trend. There’s a huge opportunity for “industrial IoT” and “Smart Cities” to impact the world in the same capacity – especially during critical situations. For example, a community water dam that needs to release water can leverage embedded critical communications logic to alert the appropriate individuals, on the right device, as soon as they are needed to take action.
SYS-CON Events announced today that HPM Networks will exhibit at the 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. For 20 years, HPM Networks has been integrating technology solutions that solve complex business challenges. HPM Networks has designed solutions for both SMB and enterprise customers throughout the San Francisco Bay Area.
SYS-CON Events announced today that Micron Technology, Inc., a global leader in advanced semiconductor systems, will exhibit at the 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. Micron’s broad portfolio of high-performance memory technologies – including DRAM, NAND and NOR Flash – is the basis for solid state drives, modules, multichip packages and other system solutions. Backed by more than 35 years of technology leadership, Micron's memory solutions enable the world's most innovative computing, consumer,...
As more intelligent IoT applications shift into gear, they’re merging into the ever-increasing traffic flow of the Internet. It won’t be long before we experience bottlenecks, as IoT traffic peaks during rush hours. Organizations that are unprepared will find themselves by the side of the road unable to cross back into the fast lane. As billions of new devices begin to communicate and exchange data – will your infrastructure be scalable enough to handle this new interconnected world?
Through WebRTC, audio and video communications are being embedded more easily than ever into applications, helping carriers, enterprises and independent software vendors deliver greater functionality to their end users. With today’s business world increasingly focused on outcomes, users’ growing calls for ease of use, and businesses craving smarter, tighter integration, what’s the next step in delivering a richer, more immersive experience? That richer, more fully integrated experience comes about through a Communications Platform as a Service which allows for messaging, screen sharing, video...
SYS-CON Events announced today that Pythian, a global IT services company specializing in helping companies leverage disruptive technologies to optimize revenue-generating systems, has been named “Bronze Sponsor” of SYS-CON's 17th Cloud Expo, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. Founded in 1997, Pythian is a global IT services company that helps companies compete by adopting disruptive technologies such as cloud, Big Data, advanced analytics, and DevOps to advance innovation and increase agility. Specializing in designing, imple...
In his session at @ThingsExpo, Lee Williams, a producer of the first smartphones and tablets, will talk about how he is now applying his experience in mobile technology to the design and development of the next generation of Environmental and Sustainability Services at ETwater. He will explain how M2M controllers work through wirelessly connected remote controls; and specifically delve into a retrofit option that reverse-engineers control codes of existing conventional controller systems so they don't have to be replaced and are instantly converted to become smart, connected devices.
SYS-CON Events announced today that IceWarp will exhibit at the 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. IceWarp, the leader of cloud and on-premise messaging, delivers secured email, chat, documents, conferencing and collaboration to today's mobile workforce, all in one unified interface
As more and more data is generated from a variety of connected devices, the need to get insights from this data and predict future behavior and trends is increasingly essential for businesses. Real-time stream processing is needed in a variety of different industries such as Manufacturing, Oil and Gas, Automobile, Finance, Online Retail, Smart Grids, and Healthcare. Azure Stream Analytics is a fully managed distributed stream computation service that provides low latency, scalable processing of streaming data in the cloud with an enterprise grade SLA. It features built-in integration with Azur...
Akana has announced the availability of the new Akana Healthcare Solution. The API-driven solution helps healthcare organizations accelerate their transition to being secure, digitally interoperable businesses. It leverages the Health Level Seven International Fast Healthcare Interoperability Resources (HL7 FHIR) standard to enable broader business use of medical data. Akana developed the Healthcare Solution in response to healthcare businesses that want to increase electronic, multi-device access to health records while reducing operating costs and complying with government regulations.
For IoT to grow as quickly as analyst firms’ project, a lot is going to fall on developers to quickly bring applications to market. But the lack of a standard development platform threatens to slow growth and make application development more time consuming and costly, much like we’ve seen in the mobile space. In his session at @ThingsExpo, Mike Weiner, Product Manager of the Omega DevCloud with KORE Telematics Inc., discussed the evolving requirements for developers as IoT matures and conducted a live demonstration of how quickly application development can happen when the need to comply wit...
The Internet of Everything (IoE) brings together people, process, data and things to make networked connections more relevant and valuable than ever before – transforming information into knowledge and knowledge into wisdom. IoE creates new capabilities, richer experiences, and unprecedented opportunities to improve business and government operations, decision making and mission support capabilities.