Chapter 2 The DynaScript Language
You do not have to declare DynaScript variables or assign them to a fixed datatype. A variable must have a value before you use it in an expression; otherwise a runtime warning is generated.
Each variable is identified by a case-sensitive name. Variable names must start with a lowercase or uppercase letter or an underscore character ( _ ). Subsequent characters can be letters, underscores, or digits. No other characters are allowed in variable names.
These are examples of valid variable names:
x
_magic
current_product
Product99
These are invalid variable names:
x 1
3magic
current!product
Product-99
R&D
Although you are not required to declare variables
in DynaScript, Sybase recommends that you do so. This is not only
good programming style, but can also avoid scoping problems with
other global variables. Declare a variable using the var
keyword.
This statement declares a variable named x
and
assigns it a value of 35
:
var x = 35;
For more information on the var
statement,
see "Statements".
Scripts use the following datatypes:
For more information on the operators that work with these datatypes, see "Operators".
Assign a value to a variable using the =
operator,
just as in many other programming languages. In DynaScripts, however,
assigning a value to a variable also sets the datatype of the variable.
For example, the following statement assigns
the value 23
to the variable x
:
x = 23 ;
If no variable named x
exists
in the current scope, one is automatically created.
You can later assign a different datatype to
the variable x
, using an
assignment statement like this:
x = "Now I am a string" ;
The following two statements successively assign
a Boolean value of true
and then
a null
(unknown) value
to the variable status
:
status = true ;
status = null ;
Variables have a scope: that is, they exist for part or all of a script or a template. You can use global variables anywhere in a template, but you can use local variables only within the current function.
If you do not explicitly declare a variable,
it is created as a global variable. For example, if the first time
that the variable x
is
referred to is in a statement like this:
x = 35 ;
then x
is
a global variable, and can be used (and will have the same value) anywhere
in the HTML template.
If you declare a local variable with the same name as an existing global variable, references to that variable name will use the local variable.
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