Q45686: How to Round Up a Fraction to Its Integral Ceiling in BASIC

Article: Q45686
Product(s): See article
Version(s): 1.00 1.01 1.02 2.00 2.01 3.00 4.00 4.00b 4.50
Operating System(s): MS-DOS
Keyword(s): ENDUSER | B_BasicCom B_GWBasicI B_BasicInt B_BBasic B_MQuickB | mspl13_basic
Last Modified: 13-DEC-1989

The mathematical ceiling function (which rounds up to the next higher
integral value for any fraction) is not built into the BASIC language.
To compute the ceiling, use the following function:

   DEF FNceil#(x#) = -INT(-x#)

   x# = 50.0001
   PRINT FNceil#(x#)    ' Prints 51

This function is equivalent to the ceil() function in the C language.

This function works in the following products:

1. Microsoft QuickBASIC Version 1.00 for the Macintosh

2. Microsoft BASIC Compiler Version 1.00 for the Macintosh

3. Microsoft BASIC Interpreter Versions 1.00, 1.01, 2.00, 2.10, and
   3.00 for the Macintosh

4. Microsoft QuickBASIC Compiler Versions 1.00, 1.01, 1.02, 2.00,
   2.01, 3.00, 4.00, 4.00b, 4.50 for the IBM PC

5. Microsoft BASIC Compiler Versions 5.35 and 5.36 for MS-DOS

6. Microsoft BASIC Compiler Versions 6.00 and 6.00b and Microsoft
   BASIC PDS Version 7.00 for MS OS/2 and MS-DOS

7. Microsoft GW-BASIC Interpreter Versions 3.20, 3.22, and 3.23 for
   MS-DOS

The code example below can be used in Microsoft QuickBASIC Versions
4.00, 4.00b, and 4.50 for MS-DOS and in Microsoft BASIC Compiler
Versions 6.00 and 6.00b and Microsoft BASIC PDS Version 7.00 for
MS-DOS and MS OS/2, but not in earlier versions:

DECLARE FUNCTION ce& (x#)   ' Function returns long integer
DECLARE FUNCTION ceil# (x#) ' Function returns double precision
CLS
x# = 40000005.001#
y# = 50.000000000001#
PRINT ceil#(x#)  ' Prints 40000006
PRINT ceil#(y#)  ' Prints 51
PRINT ce&(y#)    ' Prints 51
PRINT ce&(x#)    ' Prints 40000006
FUNCTION ceil# (x#) STATIC
ceil# = -INT(-x#)  ' Can pass values of x# in double-precision range
END FUNCTION

FUNCTION ce& (x#) STATIC
ce& = -INT(-x#)    ' Values of x# outside -2147483648 to 2147483647
END FUNCTION       ' will give a long-integer overflow error.

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