Page 123 - DCAP512_WAP_AND_WML

Unit 9: Working with user Input

Notes
Table 9.1: Example Name Value Pair
Variable Name Variable Value
MyAge 31

A sample variable table is shown in Table 9.1. If variable data is not drawn from an earlier card
or a database, the initial value must be set. This can be done within a card using either
onenterforward or ontimer.
As we may recall, onenterforward effectively creates a card that is never seen by the user but can
be used by the browser. The ontimer binding sets the variable after a (very) brief pause.

Variable escaping is typically used within URLs (also called URL escaping) to replace particular
characters with ones that have a lower chance of misinterpretation or incorrect translation.

!
Caution Typically “safe” characters are ASCII letters, digits, and some punctuation (%)
marks.

Variables

 It can be used in content.
 It can be used in some attribute values.
 It cannot be used for element or attribute names.
 It can be used to store captured user inputs.
 Variable value is set using <setvar> or control name attribute.
<setvar name =”first name” value=”Adam”/>

<input name =”firstname”/>
Anytime a single dollar sign is used in our text, it is seen as a variable reference. In order to
avoid this usage, we use two-dollar signs ($$) when referring to the currency. We can also use
the character reference form (&36), but again, it must be added.
Parentheses can be omitted if there is white space (<space> or <enter>) following a variable. Thus,
$time does not need them, but $date does. For consistency, it may be best to always use them.

Notes When a user switches from card to card in a deck, we need to store data in variables.
WML variables are case sensitive.

Specify a Variable with the Setvar Command

When someone executes a task (like go, prev, and refresh), the setvar element can be used to set
a variable with a specified value.
The following example will create a variable named i with a value of 500:
<setvar name=”i” value=”500"/>

The name and value attributes are required.

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