MACROMEDIA ColdFusion MX, Develop Manual

Page: 117 / 860

Creating and using structures 117
Adding data elements to structures
You add an element to a structure by assigning the element a value or by using a ColdFusion
function. It is cleaner and more efficient to use direct assignment, so only this technique is
described.
You add structure key-value pairs by defining the value of the structure key, as shown in the
following example:
<cfset myNewStructure.key1="A new structure with a new key">
<cfdump var=#myNewStructure#>
<cfset myNewStructure.key2="Now I’ve added a second key">
<cfdump var=#myNewStructure#>
Updating values in structures
You can update structure element values by assignment or by using the
StructUpdate
function.
Direct assignment results in simpler code than using a function, so only the assignment technique
is described.
To update a structure value, assign the key a new value. For example, the following code uses
cfset
and object.property notation to create a new structure element called departments.John,
and changes John’s department from Sales to Marketing. It then uses associative array notation to
change his department to Facilities. Each time the department changes, it displays the results:
<cfset departments=structnew()>
<cfset departments.John = "Sales">
<cfoutput>
Before the first change, John was in the #departments.John# Department<br>
</cfoutput>
<cfset Departments.John = "Marketing">
<cfoutput>
After the first change, John is in the #departments.John# Department<br>
</cfoutput>
<cfset Departments["John"] = "Facilities">
<cfoutput>
After the second change, John is in the #departments.John# Department<br>
</cfoutput>
Getting information about structures and keys
The following sections describe how to use ColdFusion functions to find information about
structures and their keys.
Getting information about structures
To find out if a given value represents a structure, use the
IsStruct
function, as follows:
IsStruct( variable )
This function returns True if variable is a ColdFusion structure. (It also returns True if variable is
a Java object that implements the java.util.Map interface.)
Structures are not indexed numerically, so to find out how many name-value pairs exist in a
structure, use the
StructCount
function, as in the following example:
StructCount(employee)