WMLScript
Data Types
Like
JavaScript, WMLScript is weakly typed. WMLScript has only one type of
variable, which is var. However, WMLScript variables are actually
handled as five primitive data types internally. A variable can be
used to store a value of any of the five primitive data types. The
data types supported in WMLScript are:
1.
Boolean. A Boolean value can be true or false.
Examples:
var
variable1 = true;
var variable2 = false;
2.
Integer. WMLScript uses 32-bit integers with two's complement. This
means an integer value can be in the range from -232/2 to
232/2-1, i.e. -2147483648 to 2147483647.
Examples:
var
variable1 = 10000;
var variable2 = -10000;
3.
Float. WMLScript uses 32-bit single precision format to represent
floating-point numbers. The maximum value supported is
3.40282347E+38. The smallest positive nonzero value supported is
1.17549435E-38. Note that some mobile devices do not support
floating-point numbers. The float()
function of WMLScript's
Lang standard library can be used to check whether a mobile
device supports floating-point numbers.
Examples:
var
variable1 = 11.11;
var variable2 = -11.11;
4.
String. A string contains some characters.
Example:
var
variable = "WMLScript Tutorial";
5.
Invalid. This is used to indicate that a variable is invalid.
Example:
var
variable = invalid;
Sometimes
the result of an operation is of the invalid type. This means errors
have occurred during the operation. One example is the divide-by-zero
error:
var
variable = 100 / 0;
After
the execution of the above script, variable contains the
invalid value. You can use the isvalid
operator to find out whether a variable is of the invalid data
type. It will be covered shortly in this WMLScript tutorial.
The
data types of operands determine the action of an operator. For
example, + is both the addition operator and the string concatenation
operator. If the operands of the + operator are numeric values, the
addition operation will be done. For example, the result of 10+15 is
25. If any operands of the + operator are of the string data type, the
string concatenation operation will be done. For example, the result
of "10"+"15" is "1015". The WMLScript
interpreter will carry out a data type conversion automatically if
necessary. For example, if the WMLScript interpreter encounters the
operation 10+"15", the numeric value 10 will first be
converted to the string data type. After that the string
concatenation operation will be performed. The result will be "1015".
|
Feedback Form (ExpandCollapse)
|
|
