1. Variables and Conditions Nicholas Tunney Senior Software Architect

2. What will we cover? Variable Basics Types of Variables
ColdFusion Variable Scopes
Conditional Logic

3. What is a variable? Container Name/value pair Dynamic (changing)
Variables permit our programs to work with values that can't be known at design time or that may change from their original value

4. Data typing Different data types hold different types of values
String: “Hello World”
Int: 42
Structure:
Object (Car)
Name
Nic Tunney
Presenter
True
Age 28
getModel()
Return string
getMake()
accelerate()

5. Strong data typing
Must declare a variable’s type before it can be used
String myName;
Int myAge;
Company myEmployer;
Strongly typed languages
Java C#

6. Weak data typing
Language determines type of variable at runtime dynamically
Weakly typed languages are NOT untyped languages
Weakly typed languages
Smalltalk
ColdFusion

7. ColdFusion data types Simple: Strings (lists) Integers Real numbers
Boolean values
Date-time values

8. ColdFusion data types Binary Object Raw data such as images COM CORBA
Java
Web Services
ColdFusion Components

9. ColdFusion data types
Complex:
Arrays
Structures
Queries

10. ColdFusion Arrays Array: Array Element
A set of sequentially indexed elements having the same type of data. Each element of an array has a unique identifying index number. Changes made to one element of an array do not affect the other elements.
Array Element
Individual item stored within an array

11. One Dimensional Arrays
Simple ordered stack of values
Addressable
Refer to each element using [x]
myArray[1], myArray[2]
myArray 1
Nic 2
Kelly 3
Simon

12. Two Dimensional Arrays
Collection of ordered values
Addressable
Refer to each element as [x][y]
myArray[1][1], myArray[2][2]
myArray 1 2
Nic
Tunney
Simon
Horwith

13. ColdFusion Structures
A container (variable) that’s holds a group of data objects. Unlike arrays, each data object in a structure generally is of a different type
Structures are unordered
Addressable
myStruct.speaker, myStruct[“topic”]
myStruct
speaker
Nic Tunney
topic
Variables
isActive
true

14. ColdFusion Queries
Series of 1 or more rows with column or field values for each row
Addressable
products.price – refers to current row
products.price[2] – specifies row
myQuery id
price
description
001
29.99
Widget
002
59.99
Foobar

15. Objects
Objects are fundamentally different from all other data types in that they encapsulate both data and behavior
Objects are real world representations
Car
getMake(): string
addGas(gallons): void
accelerate(): void

16. ColdFusion Scopes A variable typically has a lifespan and a scope
lifespan: how long the system keeps a reference to a variable
scope: location from which variable is visible
In ColdFusion, a variable's scope and lifespan are bound together in a single attribute, scope, which is prefixed to the variable name

17. ColdFusion Scopes prefix visibility prefix required lifespan
application
everywhere in same app
Yes
life of application
attributes
within custom tag (for variables passed into custom tag)
current request
caller
within custom tag (for variables on calling page)
cgi
everywhere No
client
everywhere in same application for an individual user
varies by purge timeframe
cookie
everywhere in all apps on domain
varies; set by cookie
form
request
server
everywhere by all apps on single server
varies by server timeout setting
session
everywhere in same app for an individual user
varies by session timeout setting
url
variables
local to page/CFC and any included pages (default)

18. Conditional Expressions
A conditional is an expression that can be evaluated to a boolean value
Certain actions are taken depending on true versus false

19. <cfif> Evaluates an expression <cfif expression>
Do Something
</cfif>

20. <cfelseif>
Allows us to add additional conditions if first condition is false
<cfif expression>
Do something
<cfelseif different_expression>
Do something else
</cfif>

21. <cfelse> Handles the false condition of a <cfif> block
“Catch All” condition
<cfif expression>
Do something
<cfelse>
Do something else
</cfif>

22. <cfswitch><cfcase>
Rule of threes
Evaluates expression and passes control to the matching <cfcase> tag
<cfswitch expression = "expression">
<cfcase value = "value" delimiters = "delimiters">
HTML and CFML tags
</cfcase>
… additional <cfcase></cfcase> tags …
<cfdefaultcase>
</cfdefaultcase>
</cfswitch>

23. Operators ColdFusion Operator Equivalent to IS, EQUALS, EQ = LT <
LTE, LE
<= GT
>
GTE, GE
>=
IS NOT, NEQ
<>
CONTAINS
N/A
DOES NOT CONTAIN

24. Conclusion Variables are dynamic (changing)
Variables give context and constraint to values
Experiment with complex variables to help ease coding and maintenance time
ColdFusion is a loosely typed language, but not untyped
Conditionals allow us to execute commands based on the result of some run time boolean value

25. Conclusion
This presentation laid the ground work for using variables and conditions in ColdFusion
Next steps
CF Tags
Functions for complex data types
AboutWeb Training
Fast Track to ColdFusion
Custom Class

26. Thanks!