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DTML Basics (part 2)
Find out more about DTML's conditional expressions and comparison operators

| If Only... |

The first - and simplest - decision-making routine is the "if" statement, which generally looks like this:


<dtml-if id>
do this!
</dtml-if>


The "condition" here refers to a conditional expression, which evaluates to either true or false.

Let's look at a piece of code to understand this better. Here's a DTML Method named "ifOnly", created in the same "DTML Basics" folder I used last time.


<dtml-if id>
<p>Variable "id" exists and has the value <dtml-var id>.</p>
</dtml-if>

<dtml-if myName>
<p>Variable "myName" exists and has the value "<dtml-var myName>".</p>
</dtml-if>


Now, when you view the output of this Method, you should see the following:

''.preg_replace(array('/  /', '/ /'), array('  ', '   '), '
Variable "id" exists and has the value DTML Basics.
').'
'

If you take a close look at the code above, you'll see that it includes two "if" statements; however, only one is displayed in the output. This is because the first statement evaluated to a true value, because the variable "id" exists and has a value (the name of the container within which the DTML Method is stored). However, the second DTML variable "myName" does not exist. As a result, the corresponding "if" statement evaluates as false, and so, the text enclosed within the <dtml-if> block is not displayed.


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