QBasic
                     en.wikibooks.org
                June 11, 2019
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                  Contents
                  1 QBasic/Print version                                                                            3
                  2 Introduction                                                                                    5
                  3 Basic Input                                                                                     7
                      3.1   6INPUT.BAS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .        7
                      3.2   INPUT # and LINE INPUT . . . . . . . . . . . . . . . . . . . . . . . . . .              8
                  4 Text Output                                                                                     9
                      4.1   Your first QBasic program: 1HELLO.BAS . . . . . . . . . . . . . . . . . . .              9
                      4.2   1HELLO.BAS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .          9
                      4.3   PRINT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .       9
                      4.4   2HELLO.BAS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .          9
                      4.5   PRINT, Commas, Semicolons and CLS . . . . . . . . . . . . . . . . . . . .              10
                      4.6   3HELLO.BAS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .         10
                      4.7   Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .    10
                      4.8   4FACE.BAS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .        10
                      4.9   LOCATEstatement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .          11
                      4.10 5FACE.BAS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .         11
                      4.11 COLOR statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .         11
                      4.12 Color by Number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .       12
                      4.13 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .       12
                  5 Basic Math                                                                                     13
                      5.1   Equation Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .     13
                      5.2   7MATH.BAS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .        13
                      5.3   Understanding 7MATH.BAS . . . . . . . . . . . . . . . . . . . . . . . . . .            14
                      5.4   8MATH.BAS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .        14
                      5.5   Understanding 8MATH.BAS . . . . . . . . . . . . . . . . . . . . . . . . . .            14
                      5.6   9TIP.BAS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .     14
                      5.7   Tip Calculator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .     15
                      5.8   10OROP.BAS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .        15
                      5.9   Parentheses and Order of Operations . . . . . . . . . . . . . . . . . . . . . .        16
                      5.10 Random Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .          16
                      5.11 11RND.BAS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .         16
                      5.12 More on RND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .         16
                  6 Flow Control                                                                                   19
                      6.1   Conditional execution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .      19
                      6.2   True or False . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .    19
                                                                                                                   III
                     Contents
                         6.3   IF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .    19
                         6.4   IF...THEN...ELSE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .        20
                         6.5   13 ELSEIF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .       20
                         6.6   FOR...NEXT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .        20
                         6.7   14FOR.BAS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .         21
                         6.8   WHILE...WEND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .          21
                         6.9   15WHILE.BAS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .         21
                         6.10 DO...LOOP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .        21
                         6.11 12IF.BAS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .       22
                         6.12 SELECT CASE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .            22
                     7 Advanced Input                                                                                  25
                         7.1   INKEY$. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .       25
                         7.2   The keyboard buffer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .        25
                         7.3   Scancodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .     26
                     8 Subroutines and Functions                                                                       27
                         8.1   Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .     27
                         8.2   Procedure vs. Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . .        27
                         8.3   GOTOandGOSUB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .              27
                         8.4   ONERROR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .           28
                         8.5   Declaring a subroutine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .      28
                         8.6   Declaring a function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .      29
                     9 Arrays and Types                                                                                31
                         9.1   Built-in Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .      31
                         9.2   User-defined type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .      31
                         9.3   Array . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .     32
                         9.4   Multidimensional array . . . . . . . . . . . . . . . . . . . . . . . . . . . . .        32
                         9.5   Non-zero base . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .     32
                     10 Files                                                                                          33
                         10.1 The OPEN statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .           33
                         10.2 Input and output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .       34
                         10.3 Reading the file from disk . . . . . . . . . . . . . . . . . . . . . . . . . . . .        34
                         10.4 Writing a file to the disk . . . . . . . . . . . . . . . . . . . . . . . . . . . . .      35
                     11 Advanced Text Output                                                                           37
                         11.1 Cursor manipulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .        37
                         11.2 Color    . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   37
                         11.3 Formatted printing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .       37
                     12 Sound                                                                                          39
                         12.1 BEEP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .       39
                         12.2 SOUND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .        39
                         12.3 PLAY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .       40
                         12.4 Simple Musical Keyboard In Qbasic . . . . . . . . . . . . . . . . . . . . . .            40
                     13 Graphics                                                                                       43
                     IV