How to Enter Extended ASCII Characters in QB.EXE Using ALT Key

To enter most ASCII character byte values in the QB.EXE editor, including characters without their own keys, you can hold down the ALT key while typing in the numeric value for the character on the numeric keypad and then releasing the ALT key. The character with that code will be inserted at the current cursor position. For example, ALT+1+7+2 is the symbol for one-fourth (1/4).

Extended ASCII characters (values 128 to 255) are useful for typing line-drawing characters, foreign alphabet characters, or other special symbols into quoted strings or comments (REM or ') in your code. For example, QCARDS.BAS for QuickBasic 4.50 uses extended ASCII characters to make attractive screen boxes.

This information applies to QB.EXE in Microsoft QuickBasic Versions 2.00, 2.01, 3.00, 4.00, 4.00b, and 4.50 for MS-DOS, to QB.EXE in Microsoft Basic Compiler Versions 6.00 and 6.00b for MS-DOS, and to QBX.EXE in Microsoft Basic Professional Development System (PDS) Version 7.00 and 7.10 for MS-DOS.

Most of the ASCII characters (32 through 255) can be entered using the ALT key, including the normal alphabetic characters. For example, if the ALT key is held down while the number 65 is typed on the numeric keypad (with NUM LOCK active) and then ALT is released, "A" is inserted at the current cursor position, since the ASCII code for "A" is 65 (decimal). This ALT key technique also works at the MS-DOS command line and in many other programs in MS-DOS.

How to Handle ASCII 0-31 Control Codes

Note that you cannot use the above ALT key method to embed ASCII character codes 0 through 31 into your source code. (ASCII characters 0 through 31, which are often called control characters, have special program-specific meanings.) You also cannot type ASCII 240 using the ALT key in QB.EXE or QBX.EXE (ALT+2+4+0). If you want to use a character with ASCII value 0-31 or 240 as output from your Basic program, you can use the CHR$() function to generate the character. The CHR$() function can be used to generate any ASCII (0-127) or extended-ASCII (128-255) character for output from a Basic program.

However, in QuickBasic 4.00, 4.00b, and 4.50, and in Microsoft Basic Compiler Versions 6.00 and 6.00b, the PRINT statement does not display any character for control codes 7, 9-13, and 28-31 at run time (whether the character is embedded in a string with CTRL+P or created with the CHR$() function). For more information, query on the following words: NOTE: In QB.EXE 4.00 and later and in QBX.EXE 7.00 and 7.10, you can use the CTRL+P key to enter some of the control codes from 1 through 31. As an example, for 1 press CTRL+P+A, for 2 press CTRL+P+B, for 3 press CTRL+P+C, ..., and for 31 press CTRL+P+_ (CTRL+P+underscore). Many of these control codes can be typed into string constants or comments in your source code. WARNING: BC.EXE may not accept some control codes embedded in your source file. Also, the QBX.EXE editor does not let you enter the following CTRL+P sequences: CTRL+P+@ (0), CTRL+P+J (10), CTRL+P+M (13), CTRL+P+\ (28), or CTRL+P+^ (30). Microsoft recommends using the CHR$() function to generate the control characters you need instead of typing control characters directly into the source file.

References for ASCII Symbols 0-255

The numeric character codes 0-255 are documented in the following ASCII and extended-ASCII tables:

1. In the QuickBasic 4.50 QB Advisor online Help system under Contents, "ASCII Character Codes"
2. In the Microsoft Advisor online Help system for Basic PDS 7.00 under Contents, "ASCII Character Codes"
3. Pages 464-465 of "Microsoft QuickBasic 4.0: Basic Language Reference" manual for Versions 4.00 and 4.00b
4. Pages 464-465 of "Microsoft Basic Compiler 6.0: Basic Language Reference" for Versions 6.00 and 6.00b for MS OS/2 and MS-DOS
5. Pages 602-603 of "Microsoft Basic 7.0: Language Reference"