Editing Liberty BASIC (section)

=== Distinguishing features ===
Liberty BASIC allows for procedural programming using a default "main window" that displays formatted text and accepts user input. It also supports event-driven programming based on a [[graphical user interface]], using several types of windows that may contain the standard controls such as buttons, menus, textboxes, etc.

A central idea in creating Liberty BASIC was to model the handling of windows after the [[syntax]] for file handling. For example, (from the Liberty BASIC Help File):

"The OPEN command opens communication with a device, which can be a disk file, a window, a dynamic-link library or a serial communications port."

<syntaxhighlight lang="QBasic">OPEN device FOR purpose AS #handle {LEN = n}</syntaxhighlight>

Once a “device” is open, data and also commands to control that device can be “printed” to it. For each type of device there is a set of commands which can be sent to it in this way. In the more recent versions of LB the word "print" may be dropped from the "print" statement, making the syntax even simpler.

Simplicity has been at the heart of Liberty BASIC from the beginning. This makes it easier to learn but at some cost, perhaps, in limiting functionality. Only two data types are supported in LB v4.03&nbsp;— numeric and string.  No type declarations are required; any variable with a $ sign at the end of its name is a string variable, otherwise it is numeric. (The plan for LB v5 is to support other types and user defined types as well as these.) For the purpose of making calls to an API or third-party DLLs there is a STRUCT and the additional types necessary for the DLL. The only other data structure supported is the ARRAY. Arrays of one or two dimensions are supported.  LB v5 may support arrays of user-defined types.