User Guide

88 Chapter 4: Using Expressions and Number Signs
About the Evaluate function
The
Evaluate function takes one or more string expressions, dynamically evaluates their contents
as expressions from left to right, and returns the result of evaluating the rightmost argument.
The following example shows the
Evaluate function and how it works with ColdFusion variable
processing:
<cfset myVar2="myVar">
<cfset myVar="27/9">
<cfoutput>
#myVar2#<br>
#myVar#<br>
#Evaluate("myVar2")#<br>
#Evaluate("myVar")#<br>
#Evaluate(myVar2)#<br>
#Evaluate(myVar)#<br>
</cfoutput>
Reviewing the code
The following table describes how ColdFusion processes this code:
Code Description
<cfset myVar2="myVar">
<cfset myVar="27/9">
Sets the two variables to the following strings:
myVar
27/9
<cfoutput>
#myVar2#<br>
#myVar#<br>
Displays the values assigned to the variables, myVar and 27/9,
respectively.
#Evaluate("myVar2")#<br>
Passes the string "myvar2" (without the quotation marks) to the
Evaluate function, which does the following:
1 Evaluates it as the variable myVar2.
2 Returns the value of the myVar2 variable, the string "myvar"
(without the quotation marks).
#Evaluate("myVar")#<br>
Passes the string "myvar" (without the quotation marks) to the
Evaluate function, which does the following:
1 Evaluates it as the variable myVar.
2 Returns the value of the myVar variable, the string "27/9"
(without the quotation marks).
#Evaluate(myVar2)#<br>
Evaluates the variable myVar2 as the string "myVar" and passes
the string (without the quotation marks) to the Evaluate function.
The rest of the processing is the same as in the previous line.
#Evaluate(myVar)#<br>
</cfoutput>
Evaluates the variable myVar as the string "27/9" (without the
quotation marks), and passes it to the Evaluate function, which
does the following:
1 Evaluates the string as the expression 27/9
2 Performs the division.
3 Returns the resulting value, 3