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33
DEVELOPING
COLDFUSION 9 APPLICATIONS
The CFML Programming Language
Las
t
upda
te
d 8/5/2010
Note:
ColdFusion does not have a data type for unlimited precision decimal numbers, but it can represent such numbers
as strings and provides a function that supports unlimited precision decimal arithmetic. For more information, see
PrecisionEvaluate in the CFML Reference.
For more information on ColdFusion data types, see “
Using ColdFusion Variables
” on page 38.
Flow control
ColdFusion provides several tags that let you control how a page gets executed. These tags generally correspond to
programming language flow control statements, such as if, then, and else. The following tags provide ColdFusion flow
control:
CFScript also provides a set of flow-control statements. For information on using flow-control statements in CFScript,
see “
Extending ColdFusion Pages with CFML Scripting
” on page 106. For more details on using flow-control tags, see
the reference pages for these tags in the
CFML Reference.
Category
Description and types
Simple
Represents one value. You can use simple data types directly in ColdFusion expressions. ColdFusion simple data
types are:
•
strings
A sequence of alphanumeric characters enclosed in single or double quotation marks, such as “This is
a test.”
•
integers
A sequence of numbers written without quotation marks, such as 356.
•
real numbers, such as -3.14159
•
Boolean values
Use True, Yes, or 1 for true and False, No, or 0 for false. Boolean values are not case sensitive.
•
date-time values
ColdFusion supports a variety of data formats. For more information, see “
Date and time
formats
” on page
44.
Complex
A container for data. Complex variables generally represent more than one value. ColdFusion built-in complex
data types are:
•
arrays
•
structures
•
queries
Binary
Raw data, such as the contents of a GIF file or an executable program file
Object
COM, CORBA, Java, web services, and ColdFusion Component objects: Complex objects that you create and
access using the
cfobject
tag and other specialized tags.
Tags
Purpose
cfif
,
cfelseif
,
cfelse
Select sections of code based on whether expressions are True or False.
cfswitch
,
cfcase
,
cfdefaultcase
Select among sections of code based on the value of an expression. Case processing is not limited
to True and False conditions.
cfloop
,
cfbreak
Loop through code based on any of the following values: entries in a list, keys in a structure or
external object, entries in a query column, an index, or the value of a conditional expression.
cfabort
,
cfexit
End processing of a ColdFusion page or custom tag.