Following on from the first three parts of my “Using JavaScript Operators” in ColdFusion 8 series, where I introduced Arithmetic, Assignment and Logical Operators, it is now the turn of Comparison Operators.

In the past we have been restricted to the more ‘wordy’ operators such as those defined in the first table below.

However, with the arrival of ColdFusion 8, the CFML scripting language has been brought into line with other major scripting languages. This change is undoubtedly good for ColdFusion as developers familiar with the ActionScript and JavaScript syntax can now more effectively code ColdFusion and vice-versa.

The following table describes the comparison operators that can be used in ColdFusion 8, albeit used in <cfscript> expressions only:

¹ These examples assume that var1 has been assigned the value 3 and var2 has been assigned the value 4.

Below are just a few simple examples of the new ColdFusion operators and their use:

IS EQUAL TO

In the below example, the value of var1 is not equal to var2, therefore the comparison returns false and the else statement is processed, writing the number 4 to the screen.

<cfscript>
var1 = 3;
var2 = 4;
if (var1 == var2) //returns false
	writeOutput(var1);
else
	writeOutput(var2); //writes out 4
</cfscript>

IS NOT EQUAL TO

In the below example, the variable var1 is not equal to 4, therefore the statement returns true, writing 3 to the screen. The second if statement serves to emphasise that ColdFusion is not strictly typed. Therefore comparing var1 to an Integer or a String is possible. ColdFusion handles type conversion in the background.

<cfscript>
var1 = 3;
var2 = 4;
if (var1 != 4) //returns true
	writeOutput(var1); //writes out 3
 
if (var1 != "5") //returns true
	writeOutput(var1); //writes out 3
</cfscript>

IS GREATER THAN

In the below example, var2 is greater than var1, therefore the value of var2, 4, is printed out on screen. Changing the operator to Greater Than or Equal To (>=) would also return the same result. However, using the Less Than (<) and Less Than or Equal To (<=) operators would return false and not write a value to the screen.

<cfscript>
var1 = 3;
var2 = 4;
if (var2 > var1) //returns true
	writeOutput(var2); //writes out 4
</cfscript>

Following on from my posts on Arithmetic and Assignment operators, Logical operators are typically used with Boolean (logical) values; when they are, they return a Boolean value. However, the && and || operators actually return the value of one of the specified operands, so if these operators are used with non-Boolean values, they may return a non-Boolean value.

The logical operators are described in the following table:

Using ColdFusion, the Logical operators can be expressed as follows:

Logical AND

In the below example, both operands, x and y, return true, therefore myVariable is set to true within the logical statement.

<cfscript>
x = 9;
y = 2;
myVariable = false;
 
if (x < 10 && y > 1)
{
	myVariable = true;
}
</cfscript>

Logical OR

In the below example, neither x equals 10 nor y equals 1, therefore the first part of the logical statement is not resolved. Instead, the else statement is processed, assigning the boolean value false to the variable myVariable.

<cfscript>
x = 9;
y = 2;
 
if (x == 10 || y == 1)
{
	myVariable = true;
}
else
{
	myVariable = false;
}
</cfscript>

Logical NOT

In the below example, x does not equal y. Ordinarily this would result in the logical statement being evaluated, however, a logical negation has been applied to the beginning of the expression to be evaluated, therefore the variable myVariable is assigned the boolean value true.

<cfscript>
x = 9;
y = 2;
myVariable = false;
 
if (!x==y)
{
	myVariable = true;
}
</cfscript>