User Guide

Table Of Contents
46 Chapter 3: Using ColdFusion Variables
Data type notes
Although ColdFusion variables do not have types, it is often convenient to use “variable type” as a
shorthand for the type of data that the variable represents.
ColdFusion can validate the type of data contained in form fields and query parameters. For more
information, see Chapter 26, “SELECT * FROM Departmt WHERE Dept_Name IN
('Marketing','Sales'),” on page 630 and Chapter 20, “Using cfqueryparam,” on page 473.
The
cfdump tag displays the entire contents of a variable, including ColdFusion complex data
structures. It is an excellent tool for debugging complex data and the code that handles it.
ColdFusion provides the following functions for identifying the data type of a variable:
IsArray
IsBinary
IsBoolean
IsObject
IsQuery
IsSimpleValue
IsStruct
IsXmlDoc
ColdFusion also includes the following functions for determining whether a string can be
represented as or converted to another data type:
IsDate
IsNumeric
IsXML
ColdFusion does not use a null data type. However, if ColdFusion receives a null value from an
external source such as a database, a Java object, or some other mechanism, it maintains the null
value until you use it as a simple value. At that time, ColdFusion converts the null to an empty
string (""). Also, you can use the
JavaCast function in a call to a Java object to convert a
ColdFusion empty string to a Java null.
Numbers
ColdFusion supports integers and real numbers. You can intermix integers and real numbers in
expressions; for example, 1.2 + 3 evaluates to 4.2.
ColdFusion component Chapter 10, “Building and Using ColdFusion Components,”
on page 201
Web service Chapter 36, “Using Web Services,” on page 885
Object type See