Chapter 8

A menu command that is checked shows a check mark at the beginning of the item. A menu item that is enabled can be clicked to generate a Click event. A menu command whose Enabled property is set to False is dimmed and does not generate a Click event when clicked.

Giving two or more menu items the same name creates a menu control array in which all items execute the same event procedures. The items are differentiated within the procedure by the value of the index parameter sent to the procedure.

The Print method is used for displaying text and values directly on a form.

The Select Case statement replaces a series of If-Then statements. Its syntax is:

Select Case expression
Case value1
statements if value1 = expression
Case value2

statements if value2 = expression
....
Case Else
statements executed if the expression doesn't match any of the Values
End Select

An array is a list of values in memory. Arrays have a single variable name that refers to the entire list. A subscript is a whole number that selects a single item from the list.

A non-linear difference equation of the form:

p2 = r * p1 * (1-p1)

is used as a simple mathematical model for many systems. p1 is the initial state, p2 is the final state, and r is the growth factor.