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| Paradigm | Procedural |
|---|---|
| Developer | Microsoft |
| First appeared | 1991; 34 years ago (1991) |
| Typing discipline | Static,strong |
| OS | MS-DOS,Windows 95,Windows 98,Windows Me,PC DOS,OS/2,eComStation,ArcaOS |
| License | Proprietary |
| Influenced by | |
| QuickBASIC,GW-BASIC | |
| Influenced | |
| FreeBASIC,QB64,SmallBasic | |
QBasic is anintegrated development environment (IDE) andinterpreter for a variety of dialects ofBASIC which are based onQuickBASIC. Code entered into the IDE is compiled to anintermediate representation (IR), and this IR is immediately executed on demand within the IDE.[1]
Like QuickBASIC, but unlike earlier versions of Microsoft BASIC, QBasic is astructured programming language, supporting constructs such assubroutines.[2]Line numbers, a concept often associated with BASIC, are supported for compatibility, but are not considered good form, having been replaced by descriptiveline labels.[1] QBasic has limited support for user-defined data types (structures), and several primitive types used to contain strings of text or numeric data.[3][4] It supports various inbuilt functions.
For its time, QBasic provided a state-of-the-art IDE, including adebugger with features such as on-the-fly expression evaluation and code modification.[citation needed]
QBasic was intended as a replacement forGW-BASIC. It was based on the earlierQuickBASIC 4.5 compiler but without QuickBASIC's compiler and linker elements. Version 1.0 was shipped together withMS-DOS 5.0 and higher, as well asWindows 95,Windows NT 3.x, andWindows NT 4.0.IBM recompiled QBasic and included it inPC DOS 5.x, as well asOS/2 2.0 onwards.[5]eComStation andArcaOS, descended from OS/2 code, include QBasic 1.0. QBasic 1.1 is included with MS-DOS 6.x, and, withoutEDIT, inWindows 95,Windows 98 andWindows Me. Starting withWindows 2000, Microsoft no longer includes QBasic with their operating systems.[6]
QBasic (as well as the built-inMS-DOS Editor) is backwards-compatible with DOS releases prior to 5.0 (down to at least DOS 3.20). However, if used on any8088/8086 computers, or on some80286 computers, the QBasic program may run very slowly, or perhaps not at all, due to DOS memory size limits. UntilMS-DOS 7, MS-DOS Editor andHelp required QBasic: theEDIT.COM andHELP.COM programs simply started QBasic in editor and help mode only, and these can also be entered by runningQBASIC.EXE with the/EDITOR and/QHELP switches (i.e., command linesQBASIC /EDITOR andQBASIC /QHELP).
QBasic came complete with four pre-written example programs. These wereNibbles, a variant of theSnake game;Gorillas, anartillery game;MONEY MANAGER, a personal finance manager; andRemLine, a Q-BASIC code line-number-removing program.[1]
QBasic has anEaster egg accessed by pressing and holdingLeft CTRL+Left SHIFT+Left ALT+Right CTRL+Right SHIFT+Right ALT simultaneously after running QBasic at the DOS prompt but before the title screen loads: this listsThe Team of programmers.[7]
