Dim Statement

Creates a local variable or array with the name and size (in the case of an array) and data type specified. The Static statement provides similar functionality except that the variables retain their values from one invocation of the method to the next.

Syntax

The Dim statement has two syntaxes:

Dim variableName [,variableNameN] As [ New] dataType

Part	Type	Description
variableName	Variable name	The name of the new variable.
variableNameN	Variable name	Optional. The names of other variables you wish to create with the same data type. Each name should be separated with a comma.
dataType	Data type name	The data type of the variable.
InitialValue	Same type as dataType	Initial value for variableName. If the datatype is an object that requires instantiation via the New operator, you can do that instead of assigning an initial value.

[= InitialValue]

Dim arrayName(size [,sizeN]) as dataType

Part	Type	Description
arrayName	Variable name	The name of the new array.
size	Integer	The size (number of elements) for the array.
sizeN	Integer	Optional. The size of the next dimension of the array if you are creating a multi-dimensional array.
dataType	Data type name	The data type of the array.

Notes

In the first syntax, the Dim statement is used to create new variables. A variable is an object stored in RAM that can hold a value. In the second syntax, the Dim statement is used to create a new array of the size specified. An array is simply a variable that can contain multiple values that are all the same data type. Passing more than one size parameter creates a multi-dimensional array, with the number of dimensions equal to the number of size parameters passed.

You can optionally provide an initial value to a variable declared with a Dim statement. If the variable is one of REALbasic's built-in data types ( String, Integer, Single, Double, Boolean, or Color) you can use the assignment statement to assign the initial value. Here are some examples:

Dim a as Integer =5
Dim b as Double =87.87
Dim s as String="Howdy"
Dim c as Color = &cFF4B51

The following statement initializes three variables to an initial value:

Dim x, y, z As Integer = 10

After the statement, all three variables have the same initial value.

If the data type is an object, you can optionally instantiate the object with the New operator in the Dim statement.This code declares and instantiates a Date object.

Dim d as New Date
MsgBox d.shortdate

Otherwise, you need a second line of code to instantiate the variable, d, as in the following:

Dim d as Date
d= New Date
MsgBox d.shortdate

If the call to the object's constructor takes parameters, you can pass the parameters as well. Here is an example:

Dim mb as New MemoryBlock(512)

If you write:

Dim a, b as New MemoryBlock(10)

Both a and b point to the same Memoryblock.

The Dim statement can be placed anywhere in a method or function, including inside a conditional structure (an If or Case statement).

Variables created with the Dim statement are local in scope. This means that they are created each time the method is called and are destroyed when the method is finished. The value of a local variable can be accessed only from within the method.

If you don't know the size of the array you need at the time you declare it, you can declare it as a null array, i.e., an array with no elements, and use the Redim command to resize it later. You do this by giving it an index of -1 or by leaving the parentheses empty. This means "an array of no elements." For example, the statement:

Dim aNames (-1) as String

creates the array aNames with no elements. If your program needs to load a list of names that the user enters, you can wait to size the array until you know how many names the user has entered. You can also accomplish this by leaving out the -1. The following statement is equivalent:

Dim aNames () as String

When you assign values to an array variable, such as with the Split function, you don't need to know the number of elements ahead of time.

You can also assign an array to another array. For example, the following is valid:

Dim myArray() as String
Dim newArray() as String
myArray(0)="Anthony"
myArray(1)="Aardvark"
myArray(2)="Accountant"
newArray()=myArray //newArray set equal to myArray

The Static statement provides an alternative to Dim. Static creates a local variable or local array with the name and size (in the case of an array) and data type specified. A variable declared with the Static statement and assigned a value retains its value from one invocation of the method to the next. In contrast, variables declared with the Dim statement are completely local to the method and are destroyed when each invocation of the method goes out of scope.

Examples

This example uses the Dim statement to create an Integer variable called "age" and assigns it the value 33.

Dim age As Integer
age=33

This example uses the Dim statement to create two String variables.

Dim FirstName, LastName As String

This example uses the Dim statement to create an array called aNames with 11 elements (remember, arrays have a zero element).

Dim aNames(10) As String

This example uses the Dim statement to create an array called aNames with one element.

Dim aNames(0) As String

This example uses the Dim statement to create a two-dimensional array called aNames with 11 rows and 4 columns.

Dim aNames(10,3) As String