Article: Q36901
Product(s): See article
Version(s): 4.00 4.00b 4.50
Operating System(s): MS-DOS
Keyword(s): ENDUSER | B_BasicCom floating point | mspl13_basic
Last Modified: 28-DEC-1989
The time needed to process numbers as floating-point numbers is
significantly longer than with integers. Since the default data type
is single-precision floating-point numbers, it is quite common for
people to use a floating-point variable to represent a number that
could be represented as an integer or long. A FOR-NEXT loop that does
nothing takes approximately six times as long to run when the index
variable is specified as a single-precision number rather than as an
integer.
This information applies to Microsoft QuickBASIC Versions 4.00, 4.00b,
and 4.50, to Microsoft BASIC Compiler Versions 6.00 and 6.00b for
MS-DOS and MS OS/2, and to Microsoft BASIC PDS Version 7.00 for MS-DOS
and MS OS/2.
In the following code example that multiplies zero by zero, the
version that uses integer variables runs five times as fast as the
version using floating-point variables if the computer has an 80x87
coprocessor or 25 times as fast with no coprocessor.
The results of testing with a previous version of QuickBASIC is as
follows:
The integer loop is only three times as fast under QuickBASIC Version
3.00.
The following is a code example:
' The following loop uses the default data type, single precision:
CLS
x1 = TIMER
FOR i = 1 TO 30000
j = j * j
NEXT i
x2 = TIMER
' The following loop uses integer variables:
DEFINT I-K
FOR ii = 1 TO 30000
k = k * k
NEXT
x3 = TIMER
PRINT "default loop ="; x2 - x1
PRINT "integer loop ="; x3 - x2