User Guide

Table Of Contents

90 Chapter 4: Using Expressions and Number Signs

The following example has the same result as the preceding example and is more efficient:

ProductName: #Form["product_" & i]#

</cfoutput>

In this code, ColdFusion does the following:

Evaluates the expression in the associative array index brackets as the string "product_"

concatenated with the value of the variable i.

Determines the value of the variable i; 1.

Concatenates the string and the variable value to get product_1.

Uses the result as the key value in the Form structure to get Form[product_1]. This associative

array reference accesses the same value as the object.attribute format reference Form.product_1;

in this case, Air popper.

This code format does not use any dynamic evaluation, but it achieves the same effect, of

dynamically creating a structure reference by using a string and a variable.

SetVariable function considerations

You can avoid using the

SetVariable function by using a format such as the following to set a

dynamically named variable. For example, the following lines are equivalent:

In the second line, enclosing the myVar#i# variable name in quotation marks tells ColdFusion to

evaluate the name and process any text in number signs as a variable or function. ColdFusion

replaces the #i# with the value of the variable i, so that if the value of i is 12, this code is

equivalent to the line

For more information on this usage, see “Using number signs to construct a variable name in

assignments” on page 85.

Using the IIF function

The

IIf function is a shorthand for the following code:

</cfif>

The function returns the value of the result variable. It is comparable to the use of the JavaScript

and Java ? : operator, and can result in more compact code. As a result, the

IIF function can be

convenient even if you are not using dynamic expressions.